<?xml version="1.0" encoding="us-ascii"?>
<!-- RRD ActiveDisclosure(SM) XBRL Linkbase Document - http://www.financial.rrd.com/ -->
<!-- Creation Date      : 2016-02-22T19:05:50.5948784+00:00 -->
<!-- Version            : 2.1.0.1 -->
<!-- Package ID         : 5CD61F82279090EDC61A2BE2CC587D2B-0000708819-001511 -->
<!-- Copyright (c) 2016 R. R. Donnelley & Sons Company. All Rights Reserved. -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
  <roleRef xlink:type="simple" xlink:href="mdr-20151231.xsd#TemplateLink" roleURI="http://www.mcdermott.com/20151231/role/TemplateLink" />
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/StatementCONSOLIDATEDSTATEMENTSOFEQUITY" xlink:href="mdr-20151231.xsd#Role_StatementCONSOLIDATEDSTATEMENTSOFEQUITY" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/StatementCONSOLIDATEDSTATEMENTSOFEQUITY">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityOther" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityOther" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationForfeited" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationForfeited" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:type="locator" xlink:label="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" />
    <loc xlink:href="mdr-20151231.xsd#mdr_NoncontrollingInterestIncreaseDecreaseFromSubsidiaryEquityIssuance" xlink:type="locator" xlink:label="mdr_NoncontrollingInterestIncreaseDecreaseFromSubsidiaryEquityIssuance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:type="locator" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" xlink:type="locator" xlink:label="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinorityInterestDecreaseFromRedemptions" xlink:type="locator" xlink:label="us-gaap_MinorityInterestDecreaseFromRedemptions" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProfitLoss" xlink:type="locator" xlink:label="us-gaap_ProfitLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:type="locator" xlink:label="us-gaap_NoncontrollingInterestMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ParentMember" xlink:type="locator" xlink:label="us-gaap_ParentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TreasuryStockMember" xlink:type="locator" xlink:label="us-gaap_TreasuryStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockMember" xlink:type="locator" xlink:label="us-gaap_CommonStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementTable" xlink:type="locator" xlink:label="us-gaap_StatementTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:type="locator" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_TreasuryStockMember" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_ParentMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_NoncontrollingInterestMember" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProfitLoss" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax" order="10810.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" order="11050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" order="11310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_MinorityInterestDecreaseFromRedemptions" order="11570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" order="11750.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockValueAcquiredCostMethod" order="11930.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="mdr_NoncontrollingInterestIncreaseDecreaseFromSubsidiaryEquityIssuance" order="12170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" order="12430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationForfeited" order="12650.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityOther" order="12830.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSTOCKHOLDERSEQUITYTables" xlink:href="mdr-20151231.xsd#Role_DisclosureSTOCKHOLDERSEQUITYTables" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSTOCKHOLDERSEQUITYTables">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfStockByClassTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfStockByClassTextBlock" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ReclassificationsMember" xlink:type="locator" xlink:label="mdr_ReclassificationsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLocationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationAxis" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_OtherComprehensiveIncomeLocationAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_OtherComprehensiveIncomeLocationAxis" xlink:to="us-gaap_OtherComprehensiveIncomeLocationDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_OtherComprehensiveIncomeLocationAxis" xlink:to="us-gaap_OtherComprehensiveIncomeLocationDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLocationDomain" xlink:to="mdr_ReclassificationsMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_ScheduleOfStockByClassTextBlock" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock" order="10210.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureBasisOfPresentationAndSignificantAccountingPoliciesAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureBasisOfPresentationAndSignificantAccountingPoliciesAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureBasisOfPresentationAndSignificantAccountingPoliciesAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:type="locator" xlink:label="us-gaap_DerivativeFairValueOfDerivativeLiability" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:type="locator" xlink:label="us-gaap_DerivativeFairValueOfDerivativeAsset" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesSubjectToCompromiseIncreaseDecreaseInEmployeeRelatedAccruals" xlink:type="locator" xlink:label="us-gaap_LiabilitiesSubjectToCompromiseIncreaseDecreaseInEmployeeRelatedAccruals" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PercentageOfCompletion" xlink:type="locator" xlink:label="mdr_PercentageOfCompletion" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfReportableSegments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfCountriesInWhichEntityOperates" xlink:type="locator" xlink:label="us-gaap_NumberOfCountriesInWhichEntityOperates" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember" xlink:type="locator" xlink:label="us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:type="locator" xlink:label="us-gaap_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:type="locator" xlink:label="us-gaap_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:type="locator" xlink:label="us-gaap_MachineryAndEquipmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BuildingMember" xlink:type="locator" xlink:label="us-gaap_BuildingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:type="locator" xlink:label="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:type="locator" xlink:label="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_BuildingMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_MachineryAndEquipmentMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:to="us-gaap_RangeAxis" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember_2" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_NumberOfCountriesInWhichEntityOperates" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_NumberOfReportableSegments" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_PercentageOfCompletion" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife" order="10540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_LiabilitiesSubjectToCompromiseIncreaseDecreaseInEmployeeRelatedAccruals" order="10800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_DerivativeFairValueOfDerivativeAsset" order="10950.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_DerivativeFairValueOfDerivativeLiability" order="10990.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRevenueRecognitionAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureRevenueRecognitionAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRevenueRecognitionAdditionalInformationDetail">
    <loc xlink:href="mdr-20151231.xsd#mdr_CharterContractTerm" xlink:type="locator" xlink:label="mdr_CharterContractTerm" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ProjectCompletionYear" xlink:type="locator" xlink:label="mdr_ProjectCompletionYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossOnContracts" xlink:type="locator" xlink:label="us-gaap_LossOnContracts" />
    <loc xlink:href="mdr-20151231.xsd#mdr_NumberOfProjectsInLossPosition" xlink:type="locator" xlink:label="mdr_NumberOfProjectsInLossPosition" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfRevenue" xlink:type="locator" xlink:label="us-gaap_CostOfRevenue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:type="locator" xlink:label="us-gaap_Revenues" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ActiveProjectsMember" xlink:type="locator" xlink:label="mdr_ActiveProjectsMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BacklogAssociatedWithCharterOfAgileMember" xlink:type="locator" xlink:label="mdr_BacklogAssociatedWithCharterOfAgileMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OrderOrProductionBacklogMember" xlink:type="locator" xlink:label="us-gaap_OrderOrProductionBacklogMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BacklogRelatedToActiveProjectsMember" xlink:type="locator" xlink:label="mdr_BacklogRelatedToActiveProjectsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_BR" xlink:type="locator" xlink:label="country_BR" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_MX" xlink:type="locator" xlink:label="country_MX" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:type="locator" xlink:label="us-gaap_StatementGeographicalAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AffiliateMember" xlink:type="locator" xlink:label="mdr_AffiliateMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ClaimsRevenueMember" xlink:type="locator" xlink:label="mdr_ClaimsRevenueMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:type="locator" xlink:label="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:type="locator" xlink:label="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InformationByFinancialStatementLineItemAxis" xlink:type="locator" xlink:label="us-gaap_InformationByFinancialStatementLineItemAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:type="locator" xlink:label="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:type="locator" xlink:label="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:to="us-gaap_InformationByFinancialStatementLineItemAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_InformationByFinancialStatementLineItemAxis" xlink:to="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InformationByFinancialStatementLineItemAxis" xlink:to="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:to="mdr_ClaimsRevenueMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain_2" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="mdr_AffiliateMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_2" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:to="us-gaap_StatementGeographicalAxis" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain_2" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_MX" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_BR" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="mdr_BacklogRelatedToActiveProjectsMember" order="10550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_OrderOrProductionBacklogMember" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="mdr_BacklogAssociatedWithCharterOfAgileMember" order="10590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="mdr_ActiveProjectsMember" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="us-gaap_Revenues" order="10640.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="us-gaap_CostOfRevenue" order="10840.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="mdr_NumberOfProjectsInLossPosition" order="11070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="us-gaap_LossOnContracts" order="11210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="mdr_ProjectCompletionYear" order="11350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:to="mdr_CharterContractTerm" order="11510.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureUseOfEstimatesAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureUseOfEstimatesAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureUseOfEstimatesAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfOperatingSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfOperatingSegments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainLossOnSaleOfProject" xlink:type="locator" xlink:label="us-gaap_GainLossOnSaleOfProject" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BenefitFromProjectExecutionCostSaving" xlink:type="locator" xlink:label="mdr_BenefitFromProjectExecutionCostSaving" />
    <loc xlink:href="mdr-20151231.xsd#mdr_NumberOfProjects" xlink:type="locator" xlink:label="mdr_NumberOfProjects" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EffectOnFutureEarningsOffsetAmount" xlink:type="locator" xlink:label="us-gaap_EffectOnFutureEarningsOffsetAmount" />
    <loc xlink:href="mdr-20151231.xsd#mdr_FavorableChangesDueToProductivityImprovementsAndCostReductionInitiatives" xlink:type="locator" xlink:label="mdr_FavorableChangesDueToProductivityImprovementsAndCostReductionInitiatives" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EffectOfDecreaseIncreaseInEstimatedProjectCostsOnIncome" xlink:type="locator" xlink:label="mdr_EffectOfDecreaseIncreaseInEstimatedProjectCostsOnIncome" />
    <loc xlink:href="mdr-20151231.xsd#mdr_FabricationProjectInAustraliaMember" xlink:type="locator" xlink:label="mdr_FabricationProjectInAustraliaMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EPICOneProjectInAustraliaMember" xlink:type="locator" xlink:label="mdr_EPICOneProjectInAustraliaMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EPCIProjectInAustraliaMember" xlink:type="locator" xlink:label="mdr_EPCIProjectInAustraliaMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_KJOHoutEPCIProjectNeutralZoneMember" xlink:type="locator" xlink:label="mdr_KJOHoutEPCIProjectNeutralZoneMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_KJORatawiEPCIProjectNeutralZoneMember" xlink:type="locator" xlink:label="mdr_KJORatawiEPCIProjectNeutralZoneMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SafaniyaPhaseOneSaudiAramcoEPCIProjectMember" xlink:type="locator" xlink:label="mdr_SafaniyaPhaseOneSaudiAramcoEPCIProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EPCITwoProjectsInAltamiraMember" xlink:type="locator" xlink:label="mdr_EPCITwoProjectsInAltamiraMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MarineProjectInMexicoMember" xlink:type="locator" xlink:label="mdr_MarineProjectInMexicoMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityHereemaProjectMember" xlink:type="locator" xlink:label="mdr_MorganCityHereemaProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_IchthysProjectInAustraliaMember" xlink:type="locator" xlink:label="mdr_IchthysProjectInAustraliaMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SepatFEEDAndEssoKITProjectMember" xlink:type="locator" xlink:label="mdr_SepatFEEDAndEssoKITProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BruneiProjectMember" xlink:type="locator" xlink:label="mdr_BruneiProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SiakapProjectMember" xlink:type="locator" xlink:label="mdr_SiakapProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SiakapMember" xlink:type="locator" xlink:label="mdr_SiakapMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CaspianPipelayProjectMember" xlink:type="locator" xlink:label="mdr_CaspianPipelayProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_KJORatawiProjectMember" xlink:type="locator" xlink:label="mdr_KJORatawiProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SafaniyaPhaseOneSaudiAramcoProjectMember" xlink:type="locator" xlink:label="mdr_SafaniyaPhaseOneSaudiAramcoProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SafaniyaPhaseTwoSaudiAramcoEPCIProjectMember" xlink:type="locator" xlink:label="mdr_SafaniyaPhaseTwoSaudiAramcoEPCIProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MarineInstallationProjectMember" xlink:type="locator" xlink:label="mdr_MarineInstallationProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PapaTerraProjectMember" xlink:type="locator" xlink:label="mdr_PapaTerraProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityFabricationProjectMember" xlink:type="locator" xlink:label="mdr_MorganCityFabricationProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_JackAndStMaloProjectMember" xlink:type="locator" xlink:label="mdr_JackAndStMaloProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PBLitoralEPCIProjectMember" xlink:type="locator" xlink:label="mdr_PBLitoralEPCIProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_GorgonMRUProjectMember" xlink:type="locator" xlink:label="mdr_GorgonMRUProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_IchthysProjectMember" xlink:type="locator" xlink:label="mdr_IchthysProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ProjectOneMember" xlink:type="locator" xlink:label="mdr_ProjectOneMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProjectMember" xlink:type="locator" xlink:label="us-gaap_ProjectMember_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProjectMember" xlink:type="locator" xlink:label="us-gaap_ProjectMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:type="locator" xlink:label="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ADMAFourGIProjectMember" xlink:type="locator" xlink:label="mdr_ADMAFourGIProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_KJOHoutProjectMember" xlink:type="locator" xlink:label="mdr_KJOHoutProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AbuAliCableLayProjectMember" xlink:type="locator" xlink:label="mdr_AbuAliCableLayProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherMultipleProjectsMember" xlink:type="locator" xlink:label="mdr_OtherMultipleProjectsMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AgileCharterMember" xlink:type="locator" xlink:label="mdr_AgileCharterMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PBLitoralProjectMember" xlink:type="locator" xlink:label="mdr_PBLitoralProjectMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_UseOfEstimatesByProjectDomain" xlink:type="locator" xlink:label="mdr_UseOfEstimatesByProjectDomain_2" />
    <loc xlink:href="mdr-20151231.xsd#mdr_UseOfEstimatesByProjectDomain" xlink:type="locator" xlink:label="mdr_UseOfEstimatesByProjectDomain" />
    <loc xlink:href="mdr-20151231.xsd#mdr_UseOfEstimatesByProjectAxis" xlink:type="locator" xlink:label="mdr_UseOfEstimatesByProjectAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:type="locator" xlink:label="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:type="locator" xlink:label="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:to="mdr_UseOfEstimatesByProjectAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="mdr_UseOfEstimatesByProjectAxis" xlink:to="mdr_UseOfEstimatesByProjectDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="mdr_UseOfEstimatesByProjectAxis" xlink:to="mdr_UseOfEstimatesByProjectDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_PBLitoralProjectMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_AgileCharterMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_OtherMultipleProjectsMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_AbuAliCableLayProjectMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_KJOHoutProjectMember" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_ADMAFourGIProjectMember" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" xlink:to="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:to="us-gaap_ProjectMember_2" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:to="us-gaap_ProjectMember" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProjectMember" xlink:to="mdr_ProjectOneMember" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_IchthysProjectMember" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_GorgonMRUProjectMember" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_PBLitoralEPCIProjectMember" order="10810.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_JackAndStMaloProjectMember" order="10830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_MorganCityFabricationProjectMember" order="10850.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_PapaTerraProjectMember" order="10870.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_MarineInstallationProjectMember" order="10890.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SafaniyaPhaseTwoSaudiAramcoEPCIProjectMember" order="11110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SafaniyaPhaseOneSaudiAramcoProjectMember" order="11170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_KJORatawiProjectMember" order="11190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_CaspianPipelayProjectMember" order="11210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SiakapMember" order="11620.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SiakapProjectMember" order="11640.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_BruneiProjectMember" order="11660.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SepatFEEDAndEssoKITProjectMember" order="11680.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_IchthysProjectInAustraliaMember" order="11700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_MorganCityHereemaProjectMember" order="11920.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_MarineProjectInMexicoMember" order="11940.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_EPCITwoProjectsInAltamiraMember" order="11980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_SafaniyaPhaseOneSaudiAramcoEPCIProjectMember" order="12220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_KJORatawiEPCIProjectNeutralZoneMember" order="12240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_KJOHoutEPCIProjectNeutralZoneMember" order="12260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_EPCIProjectInAustraliaMember" order="12480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_EPICOneProjectInAustraliaMember" order="12500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_UseOfEstimatesByProjectDomain" xlink:to="mdr_FabricationProjectInAustraliaMember" order="12520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_EffectOfDecreaseIncreaseInEstimatedProjectCostsOnIncome" order="12550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_FavorableChangesDueToProductivityImprovementsAndCostReductionInitiatives" order="12700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_EffectOnFutureEarningsOffsetAmount" order="12740.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_NumberOfProjects" order="12930.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="mdr_BenefitFromProjectExecutionCostSaving" order="13160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_GainLossOnSaleOfProject" order="14280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" xlink:to="us-gaap_NumberOfOperatingSegments" order="14320.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureRestructuringAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LegalAndOtherConsultingFeesMember" xlink:type="locator" xlink:label="mdr_LegalAndOtherConsultingFeesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_McDermottProfitabilityInitiativeMember" xlink:type="locator" xlink:label="mdr_McDermottProfitabilityInitiativeMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AORMember" xlink:type="locator" xlink:label="mdr_AORMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:type="locator" xlink:label="us-gaap_RestructuringPlanDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:type="locator" xlink:label="us-gaap_RestructuringPlanDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringPlanAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringPlanAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_RestructuringPlanAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_AORMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_McDermottProfitabilityInitiativeMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_RestructuringCostAndReserveAxis" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain_2" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_LegalAndOtherConsultingFeesMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" order="10280.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringRestructuringCostsIncurredAndFutureCostExpectedToBeIncurredDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureRestructuringRestructuringCostsIncurredAndFutureCostExpectedToBeIncurredDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringRestructuringCostsIncurredAndFutureCostExpectedToBeIncurredDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostExpectedCost1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCharges" xlink:type="locator" xlink:label="us-gaap_RestructuringCharges" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AORMember" xlink:type="locator" xlink:label="mdr_AORMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_McDermottProfitabilityInitiativeMember" xlink:type="locator" xlink:label="mdr_McDermottProfitabilityInitiativeMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CorporateRestructuringMember" xlink:type="locator" xlink:label="mdr_CorporateRestructuringMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestructuringOfAmericasOperationsMember" xlink:type="locator" xlink:label="mdr_RestructuringOfAmericasOperationsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:type="locator" xlink:label="us-gaap_RestructuringPlanDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringPlanAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringPlanAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AssetImpairmentMember" xlink:type="locator" xlink:label="mdr_AssetImpairmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LegalAndOtherConsultingFeesMember" xlink:type="locator" xlink:label="mdr_LegalAndOtherConsultingFeesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherChargesMember" xlink:type="locator" xlink:label="mdr_OtherChargesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityYardRelatedExpensesMember" xlink:type="locator" xlink:label="mdr_MorganCityYardRelatedExpensesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:type="locator" xlink:label="us-gaap_EmployeeSeveranceMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ImpairmentsAndWriteOffsMember" xlink:type="locator" xlink:label="mdr_ImpairmentsAndWriteOffsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityEnvironmentalAccrualMember" xlink:type="locator" xlink:label="mdr_MorganCityEnvironmentalAccrualMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:type="locator" xlink:label="us-gaap_CorporateNonSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CorporateAndOtherNonSegmentMember" xlink:type="locator" xlink:label="mdr_CorporateAndOtherNonSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" order="10030.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_ConsolidationItemsAxis" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ConsolidationItemsAxis" xlink:to="us-gaap_ConsolidationItemsDomain_2" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConsolidationItemsAxis" xlink:to="us-gaap_ConsolidationItemsDomain" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="mdr_CorporateAndOtherNonSegmentMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_CorporateNonSegmentMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_ValuationAllowancesAndReservesTypeAxis" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="us-gaap_ValuationAllowancesAndReservesDomain_2" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="us-gaap_ValuationAllowancesAndReservesDomain" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="mdr_MorganCityEnvironmentalAccrualMember" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_RestructuringCostAndReserveAxis" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_ImpairmentsAndWriteOffsMember" order="10550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="us-gaap_EmployeeSeveranceMember" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_MorganCityYardRelatedExpensesMember" order="10590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_OtherChargesMember" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_LegalAndOtherConsultingFeesMember" order="10650.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_AssetImpairmentMember" order="10770.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_RestructuringPlanAxis" order="10940.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain" order="10960.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_RestructuringOfAmericasOperationsMember" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_CorporateRestructuringMember" order="11100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_McDermottProfitabilityInitiativeMember" order="11180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="mdr_AORMember" order="11380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringCharges" order="11490.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostCostIncurredToDate1" order="15010.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" order="16450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostExpectedCost1" order="17590.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringRollForwardOfAccruedLiabilitiesAssociatedWithRestructuringActivitiesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureRestructuringRollForwardOfAccruedLiabilitiesAssociatedWithRestructuringActivitiesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureRestructuringRollForwardOfAccruedLiabilitiesAssociatedWithRestructuringActivitiesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:type="locator" xlink:label="us-gaap_PaymentsForRestructuring" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringReserveAccrualAdjustment" xlink:type="locator" xlink:label="us-gaap_RestructuringReserveAccrualAdjustment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringReserve" xlink:type="locator" xlink:label="us-gaap_RestructuringReserve" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityEnvironmentalAccrualMember" xlink:type="locator" xlink:label="mdr_MorganCityEnvironmentalAccrualMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestructuringRelatedAccrualsMember" xlink:type="locator" xlink:label="mdr_RestructuringRelatedAccrualsMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MorganCityYardRelatedExpensesAndOtherMember" xlink:type="locator" xlink:label="mdr_MorganCityYardRelatedExpensesAndOtherMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringReserveLineItems" xlink:type="locator" xlink:label="us-gaap_RestructuringReserveLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RestructuringReserveLineItems" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_RestructuringCostAndReserveAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_MorganCityYardRelatedExpensesAndOtherMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="mdr_RestructuringRelatedAccrualsMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_ValuationAllowancesAndReservesTypeAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="us-gaap_ValuationAllowancesAndReservesDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="mdr_MorganCityEnvironmentalAccrualMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringReserveLineItems" xlink:to="us-gaap_RestructuringReserve" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringReserveLineItems" xlink:to="us-gaap_RestructuringReserveAccrualAdjustment" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringReserveLineItems" xlink:to="us-gaap_PaymentsForRestructuring" order="10540.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAccountsReceivableContractReceivablesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureAccountsReceivableContractReceivablesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAccountsReceivableContractReceivablesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnbilledContractsReceivable" xlink:type="locator" xlink:label="us-gaap_UnbilledContractsReceivable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContractReceivableRetainageDueOneYearOrLess" xlink:type="locator" xlink:label="us-gaap_ContractReceivableRetainageDueOneYearOrLess" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CompletedProjectMember" xlink:type="locator" xlink:label="mdr_CompletedProjectMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorPropertyClassDomain" xlink:type="locator" xlink:label="us-gaap_MajorPropertyClassDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorPropertyClassDomain" xlink:type="locator" xlink:label="us-gaap_MajorPropertyClassDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorPropertyClassAxis" xlink:type="locator" xlink:label="us-gaap_MajorPropertyClassAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ContractReceivableMember" xlink:type="locator" xlink:label="mdr_ContractReceivableMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:type="locator" xlink:label="us-gaap_ReceivableTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:type="locator" xlink:label="us-gaap_ReceivableTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:type="locator" xlink:label="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:type="locator" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" order="10060.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:to="us-gaap_ReceivableTypeDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:to="us-gaap_ReceivableTypeDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ReceivableTypeDomain" xlink:to="mdr_ContractReceivableMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_MajorPropertyClassAxis" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorPropertyClassAxis" xlink:to="us-gaap_MajorPropertyClassDomain_2" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorPropertyClassAxis" xlink:to="us-gaap_MajorPropertyClassDomain" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MajorPropertyClassDomain" xlink:to="mdr_CompletedProjectMember" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ContractReceivableRetainageDueOneYearOrLess" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_UnbilledContractsReceivable" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_AccountsReceivableNetCurrent" order="10690.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAccountsReceivableAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureAccountsReceivableAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAccountsReceivableAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EmployeeReceivablesCollectionPeriod" xlink:type="locator" xlink:label="mdr_EmployeeReceivablesCollectionPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContractReceivableRetainageDueThreeToFourYears" xlink:type="locator" xlink:label="us-gaap_ContractReceivableRetainageDueThreeToFourYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContractReceivableRetainageDueTwoToThreeYears" xlink:type="locator" xlink:label="us-gaap_ContractReceivableRetainageDueTwoToThreeYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:type="locator" xlink:label="us-gaap_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:type="locator" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_RangeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ContractReceivableRetainageDueTwoToThreeYears" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ContractReceivableRetainageDueThreeToFourYears" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="mdr_EmployeeReceivablesCollectionPeriod" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivable" order="10280.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePropertyPlantAndEquipmentSummaryOfPropertyPlantEquipmentByAssetCategoryDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePropertyPlantAndEquipmentSummaryOfPropertyPlantEquipmentByAssetCategoryDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePropertyPlantAndEquipmentSummaryOfPropertyPlantEquipmentByAssetCategoryDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:type="locator" xlink:label="us-gaap_ConstructionInProgressMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentOtherTypesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BuildingMember" xlink:type="locator" xlink:label="us-gaap_BuildingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquipmentMember" xlink:type="locator" xlink:label="us-gaap_EquipmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_VesselsMember" xlink:type="locator" xlink:label="mdr_VesselsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="mdr_VesselsMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_EquipmentMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_BuildingMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentOtherTypesMember" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_ConstructionInProgressMember" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="10670.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDebtAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtAdditionalInformationDetail">
    <loc xlink:href="mdr-20151231.xsd#mdr_LettersOfCreditSuretyBondsAndOtherArrangements" xlink:type="locator" xlink:label="mdr_LettersOfCreditSuretyBondsAndOtherArrangements" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BankGuaranteesOutstanding" xlink:type="locator" xlink:label="mdr_BankGuaranteesOutstanding" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdministrativeFeesExpense" xlink:type="locator" xlink:label="us-gaap_AdministrativeFeesExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestments" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EquityInvestmentOwnershipPercentage" xlink:type="locator" xlink:label="mdr_EquityInvestmentOwnershipPercentage" />
    <loc xlink:href="mdr-20151231.xsd#mdr_GuaranteePercent" xlink:type="locator" xlink:label="mdr_GuaranteePercent" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DebtInstrumentNumberOfPeriodicPayment" xlink:type="locator" xlink:label="mdr_DebtInstrumentNumberOfPeriodicPayment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentPaymentTerms" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPaymentTerms" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:type="locator" xlink:label="us-gaap_SharesIssuedPricePerShare" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PotentialDilutiveSecuritiesThatCouldBeIncludedInComputationOfEarningsPerShareAmount" xlink:type="locator" xlink:label="mdr_PotentialDilutiveSecuritiesThatCouldBeIncludedInComputationOfEarningsPerShareAmount" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MaximumSettlementSharesPerTangibleUnit" xlink:type="locator" xlink:label="mdr_MaximumSettlementSharesPerTangibleUnit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesPayableCurrent" xlink:type="locator" xlink:label="us-gaap_NotesPayableCurrent" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" xlink:type="locator" xlink:label="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PrincipalAmountPerAmortizingNote" xlink:type="locator" xlink:label="mdr_PrincipalAmountPerAmortizingNote" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TangibleUnitsStatedAmountPerUnit" xlink:type="locator" xlink:label="mdr_TangibleUnitsStatedAmountPerUnit" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TangibleUnitsInterestRatePercentage" xlink:type="locator" xlink:label="mdr_TangibleUnitsInterestRatePercentage" />
    <loc xlink:href="mdr-20151231.xsd#mdr_StockIssuedDuringPeriodSharesTangibleUnits" xlink:type="locator" xlink:label="mdr_StockIssuedDuringPeriodSharesTangibleUnits" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateDuringPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent" xlink:type="locator" xlink:label="us-gaap_DividendsPayableCurrentAndNoncurrent" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LineOfCreditFacilityAggregateLeverageRatio" xlink:type="locator" xlink:label="mdr_LineOfCreditFacilityAggregateLeverageRatio" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ExcessCashFlowPercentage" xlink:type="locator" xlink:label="mdr_ExcessCashFlowPercentage" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ReinvestmentPeriod" xlink:type="locator" xlink:label="mdr_ReinvestmentPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LineOfCreditUtilizationFeeRate" xlink:type="locator" xlink:label="mdr_LineOfCreditUtilizationFeeRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCommitmentFeePercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCurrencyExchangeRateTranslation1" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyExchangeRateTranslation1" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MinimumRequiredCashBalanceCreditFacility" xlink:type="locator" xlink:label="mdr_MinimumRequiredCashBalanceCreditFacility" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EarningsBeforeInterestTaxesDepreciationAndAmortization" xlink:type="locator" xlink:label="mdr_EarningsBeforeInterestTaxesDepreciationAndAmortization" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityCovenantTerms" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCovenantTerms" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LineOfCreditFacilityCollateralAmount" xlink:type="locator" xlink:label="mdr_LineOfCreditFacilityCollateralAmount" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestrictedCashCollateralLettersOfCredit" xlink:type="locator" xlink:label="mdr_RestrictedCashCollateralLettersOfCredit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MaximumPercentageOfFinancialLetterOfCreditToLetterOfCreditFacility" xlink:type="locator" xlink:label="mdr_MaximumPercentageOfFinancialLetterOfCreditToLetterOfCreditFacility" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnsecuredDebt" xlink:type="locator" xlink:label="us-gaap_UnsecuredDebt" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TangibleShareholderEquity" xlink:type="locator" xlink:label="mdr_TangibleShareholderEquity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesIssued1" xlink:type="locator" xlink:label="us-gaap_NotesIssued1" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DebtInstrumentMaturityYear" xlink:type="locator" xlink:label="mdr_DebtInstrumentMaturityYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtIssuanceCosts" xlink:type="locator" xlink:label="us-gaap_DebtIssuanceCosts" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherGeneralReimbursementMember" xlink:type="locator" xlink:label="mdr_OtherGeneralReimbursementMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ReimbursementAgreementMember" xlink:type="locator" xlink:label="mdr_ReimbursementAgreementMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BusinessLineOneMember" xlink:type="locator" xlink:label="mdr_BusinessLineOneMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BusinessLineTwoMember" xlink:type="locator" xlink:label="mdr_BusinessLineTwoMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_NorthOceanConstructionFinancingMember" xlink:type="locator" xlink:label="mdr_NorthOceanConstructionFinancingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecuredDebtMember" xlink:type="locator" xlink:label="us-gaap_SecuredDebtMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SeniorAmortizingNoteDueAprilOneTwoThousandSeventeenMember" xlink:type="locator" xlink:label="mdr_SeniorAmortizingNoteDueAprilOneTwoThousandSeventeenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AfterAprilSixteenTwoThousandSeventeenMember" xlink:type="locator" xlink:label="mdr_AfterAprilSixteenTwoThousandSeventeenMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PriorToAprilSixteenTwoThousandSeventeenMember" xlink:type="locator" xlink:label="mdr_PriorToAprilSixteenTwoThousandSeventeenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:type="locator" xlink:label="us-gaap_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BaseRateMember" xlink:type="locator" xlink:label="us-gaap_BaseRateMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:type="locator" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateAxis" xlink:type="locator" xlink:label="us-gaap_VariableRateAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PerformanceStandByLettersOfCreditMember" xlink:type="locator" xlink:label="mdr_PerformanceStandByLettersOfCreditMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:type="locator" xlink:label="us-gaap_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialStandbyLetterOfCreditMember" xlink:type="locator" xlink:label="us-gaap_FinancialStandbyLetterOfCreditMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:type="locator" xlink:label="us-gaap_LossContingencyNatureDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:type="locator" xlink:label="us-gaap_LossContingencyNatureDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:type="locator" xlink:label="us-gaap_LossContingenciesByNatureOfContingencyAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventMember" xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AfterMarchThirtyFirstTwoThousandSixteenBeforeAprilSixteenTwoThousandSeventeenMember" xlink:type="locator" xlink:label="mdr_AfterMarchThirtyFirstTwoThousandSixteenBeforeAprilSixteenTwoThousandSeventeenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TangibleEquityUnitsMember" xlink:type="locator" xlink:label="mdr_TangibleEquityUnitsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotesMember" xlink:type="locator" xlink:label="us-gaap_SeniorNotesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TermLoanMember" xlink:type="locator" xlink:label="mdr_TermLoanMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:type="locator" xlink:label="us-gaap_LetterOfCreditMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:type="locator" xlink:label="us-gaap_CreditFacilityAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_CreditFacilityAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_LetterOfCreditMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_TermLoanMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_2" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_TangibleEquityUnitsMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_StatementScenarioAxis" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_2" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="mdr_AfterMarchThirtyFirstTwoThousandSixteenBeforeAprilSixteenTwoThousandSeventeenMember" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_SubsequentEventTypeAxis" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_2" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LossContingenciesByNatureOfContingencyAxis" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="us-gaap_LossContingencyNatureDomain_2" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="us-gaap_LossContingencyNatureDomain" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingencyNatureDomain" xlink:to="us-gaap_FinancialStandbyLetterOfCreditMember" order="10520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="mdr_TermLoanMember" order="10780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_RangeAxis" order="10790.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10810.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="10830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_PerformanceStandByLettersOfCreditMember" order="10900.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_VariableRateAxis" order="10960.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain_2" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_LondonInterbankOfferedRateLIBORMember" order="11000.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_BaseRateMember" order="11040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="11130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="mdr_PriorToAprilSixteenTwoThousandSeventeenMember" order="11390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="mdr_AfterAprilSixteenTwoThousandSeventeenMember" order="11410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" order="11510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_2" order="11530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="11530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="mdr_SeniorAmortizingNoteDueAprilOneTwoThousandSeventeenMember" order="11550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SecuredDebtMember" order="11810.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="mdr_NorthOceanConstructionFinancingMember" order="11920.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_BusinessLineTwoMember" order="12030.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_BusinessLineOneMember" order="12210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_ReimbursementAgreementMember" order="12280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="mdr_OtherGeneralReimbursementMember" order="12300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtIssuanceCosts" order="12350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" order="12460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_DebtInstrumentMaturityYear" order="12570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_NotesIssued1" order="12750.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_TangibleShareholderEquity" order="12820.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_UnsecuredDebt" order="12860.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" order="13000.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_MaximumPercentageOfFinancialLetterOfCreditToLetterOfCreditFacility" order="13070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" order="13140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_RestrictedCashCollateralLettersOfCredit" order="13310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_LineOfCreditFacilityCollateralAmount" order="13410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityCovenantTerms" order="13600.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_EarningsBeforeInterestTaxesDepreciationAndAmortization" order="13700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_MinimumRequiredCashBalanceCreditFacility" order="13800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ForeignCurrencyExchangeRateTranslation1" order="13900.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityCommitmentFeePercentage" order="14050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_LineOfCreditUtilizationFeeRate" order="14130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" order="14260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_ReinvestmentPeriod" order="14450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_ExcessCashFlowPercentage" order="14530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" order="14610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_LineOfCreditFacilityAggregateLeverageRatio" order="14720.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DividendsPayableCurrentAndNoncurrent" order="14830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateDuringPeriod" order="15000.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" order="15080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_StockIssuedDuringPeriodSharesTangibleUnits" order="15190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_TangibleUnitsInterestRatePercentage" order="15230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_TangibleUnitsStatedAmountPerUnit" order="15270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_PrincipalAmountPerAmortizingNote" order="15350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="15390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" order="15460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_NotesPayableCurrent" order="15540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_MaximumSettlementSharesPerTangibleUnit" order="15610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_PotentialDilutiveSecuritiesThatCouldBeIncludedInComputationOfEarningsPerShareAmount" order="15690.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_SharesIssuedPricePerShare" order="15810.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" order="15920.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" order="16020.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentPaymentTerms" order="16140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_DebtInstrumentNumberOfPeriodicPayment" order="16240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_GuaranteePercent" order="16570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_EquityInvestmentOwnershipPercentage" order="16630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_EquityMethodInvestments" order="16690.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_AdministrativeFeesExpense" order="16780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_BankGuaranteesOutstanding" order="16860.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="mdr_LettersOfCreditSuretyBondsAndOtherArrangements" order="17010.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtSummaryOfLongTermDebtObligationsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDebtSummaryOfLongTermDebtObligationsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtSummaryOfLongTermDebtObligationsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:type="locator" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:type="locator" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:type="locator" xlink:label="us-gaap_DebtAndCapitalLeaseObligations" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherSecuredFinancingsMember" xlink:type="locator" xlink:label="mdr_OtherSecuredFinancingsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeaseObligationsMember" xlink:type="locator" xlink:label="us-gaap_CapitalLeaseObligationsMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmortizingNotesMember" xlink:type="locator" xlink:label="mdr_AmortizingNotesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TermLoanMember" xlink:type="locator" xlink:label="mdr_TermLoanMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotesMember" xlink:type="locator" xlink:label="us-gaap_SeniorNotesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BusinessLineTwoMember" xlink:type="locator" xlink:label="mdr_BusinessLineTwoMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" order="10030.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_BusinessAcquisitionAxis" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_2" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="mdr_BusinessLineTwoMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="mdr_TermLoanMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="mdr_AmortizingNotesMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_CapitalLeaseObligationsMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="mdr_OtherSecuredFinancingsMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtAndCapitalLeaseObligations" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" order="10800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligations" order="10840.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtSummaryOfRedemptionPricesExpressedAsPercentageDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDebtSummaryOfRedemptionPricesExpressedAsPercentageDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDebtSummaryOfRedemptionPricesExpressedAsPercentageDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPricePercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotesMember" xlink:type="locator" xlink:label="us-gaap_SeniorNotesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodThreeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodTwoMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodOneMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentRedemptionLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentRedemptionLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentRedemptionTable" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodOneMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodTwoMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodThreeMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentRedemptionTable" xlink:to="us-gaap_LongtermDebtTypeAxis" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionPricePercentage" order="10200.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DefinedBenefitPlanFundedStatusOfPlanNetAmountRecognized" xlink:type="locator" xlink:label="mdr_DefinedBenefitPlanFundedStatusOfPlanNetAmountRecognized" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPensionPlanLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPensionPlanLiabilitiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFundedStatusOfPlan" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanSettlementsPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitsPaid" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitsPaid" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10050.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain_2" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanInterestCost" order="10640.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanActuarialGainLoss" order="10800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" order="10960.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanBenefitsPaid" order="11060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" order="11340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" order="11500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" order="11660.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanContributionsByEmployer" order="11820.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" order="11940.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanFundedStatusOfPlan" order="12240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" order="12400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" order="12560.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesCurrent" order="12660.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" order="12780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" order="12940.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="mdr_DefinedBenefitPlanFundedStatusOfPlanNetAmountRecognized" order="13100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" order="13290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" order="13450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" order="13610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" order="13770.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusParentheticalDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusParentheticalDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsObligationsAndFundedStatusParentheticalDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" order="10110.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsWeightedAverageAssumptionsUsedToDetermineNetPeriodicBenefitObligationsAndNetPeriodicBenefitCostDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsWeightedAverageAssumptionsUsedToDetermineNetPeriodicBenefitObligationsAndNetPeriodicBenefitCostDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsWeightedAverageAssumptionsUsedToDetermineNetPeriodicBenefitObligationsAndNetPeriodicBenefitCostDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" order="10550.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsNetPeriodicBenefitCostDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsNetPeriodicBenefitCostDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsNetPeriodicBenefitCostDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DefinedBenefitPlanActuarialGainLossOnObligationsAndPlanAssets" xlink:type="locator" xlink:label="mdr_DefinedBenefitPlanActuarialGainLossOnObligationsAndPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10040.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanInterestCost" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="mdr_DefinedBenefitPlanActuarialGainLossOnObligationsAndPlanAssets" order="10720.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" order="11240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" order="11520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" order="11780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" order="12040.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanCostRecognized" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DefinedContributionPlanContributionRatesAsPercentageOfEmployeesEarnings" xlink:type="locator" xlink:label="mdr_DefinedContributionPlanContributionRatesAsPercentageOfEmployeesEarnings" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DefinedContributionPlanMatchingPercentOfCompensation" xlink:type="locator" xlink:label="mdr_DefinedContributionPlanMatchingPercentOfCompensation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanCurrentAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanCurrentAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DefinedBenefitPlanAssumptionsUsedCalculatingPlanAssetsExpectedLongTermReturnOnAssets" xlink:type="locator" xlink:label="mdr_DefinedBenefitPlanAssumptionsUsedCalculatingPlanAssetsExpectedLongTermReturnOnAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:type="locator" xlink:label="us-gaap_ScenarioForecastMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsMember" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:type="locator" xlink:label="us-gaap_EquitySecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:type="locator" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:type="locator" xlink:label="us-gaap_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:type="locator" xlink:label="us-gaap_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RangeAxis" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain_2" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_EquitySecuritiesMember" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_CashAndCashEquivalentsMember" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_StatementScenarioAxis" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="us-gaap_ScenarioForecastMember" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="mdr_DefinedBenefitPlanAssumptionsUsedCalculatingPlanAssetsExpectedLongTermReturnOnAssets" order="10890.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" order="11080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanCurrentAssets" order="11200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" order="11290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="mdr_DefinedContributionPlanMatchingPercentOfCompensation" order="11430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="mdr_DefinedContributionPlanContributionRatesAsPercentageOfEmployeesEarnings" order="11570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanCostRecognized" order="11710.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsAssetAllocationsByAssetCategoryDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsAssetAllocationsByAssetCategoryDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsAssetAllocationsByAssetCategoryDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:type="locator" xlink:label="us-gaap_EquitySecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:type="locator" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_EquitySecuritiesMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" order="10240.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsTotalInvestmentsPlansMeasuredAtFairValueDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsTotalInvestmentsPlansMeasuredAtFairValueDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsTotalInvestmentsPlansMeasuredAtFairValueDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CashAndAccruedItemsMember" xlink:type="locator" xlink:label="mdr_CashAndAccruedItemsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:type="locator" xlink:label="us-gaap_EquitySecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:type="locator" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_EquitySecuritiesMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="mdr_CashAndAccruedItemsMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" order="10300.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsChangesInLevelThreeFixedIncomeInstrumentMeasuredOnRecurringBasisDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsChangesInLevelThreeFixedIncomeInstrumentMeasuredOnRecurringBasisDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsChangesInLevelThreeFixedIncomeInstrumentMeasuredOnRecurringBasisDetail">
    <loc xlink:href="mdr-20151231.xsd#mdr_DefineBenefitPlanUnrealizedGainLossOnPlanAssets" xlink:type="locator" xlink:label="mdr_DefineBenefitPlanUnrealizedGainLossOnPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:type="locator" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="mdr_DefineBenefitPlanUnrealizedGainLossOnPlanAssets" order="10380.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsExpectedEmployerContributionsToTrustsOfDefinedBenefitPlansDetail" xlink:href="mdr-20151231.xsd#Role_DisclosurePensionAndPostretirementBenefitsExpectedEmployerContributionsToTrustsOfDefinedBenefitPlansDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosurePensionAndPostretirementBenefitsExpectedEmployerContributionsToTrustsOfDefinedBenefitPlansDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_ForeignPensionPlansDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" xlink:type="locator" xlink:label="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:to="us-gaap_DefinedBenefitPlansDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlansDomain" xlink:to="us-gaap_ForeignPensionPlansDefinedBenefitMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" xlink:to="us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" order="10730.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" order="10830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" order="10930.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDerivativeFinancialInstrumentsAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMaturityDates" xlink:type="locator" xlink:label="us-gaap_DerivativeMaturityDates" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:type="locator" xlink:label="invest_DerivativeNotionalAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EngineeringProcurementConstructionAndInstallationMember" xlink:type="locator" xlink:label="mdr_EngineeringProcurementConstructionAndInstallationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProjectMember" xlink:type="locator" xlink:label="us-gaap_ProjectMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:type="locator" xlink:label="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:type="locator" xlink:label="us-gaap_DerivativeTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:to="us-gaap_ProjectMember" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProjectMember" xlink:to="mdr_EngineeringProcurementConstructionAndInstallationMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="invest_DerivativeNotionalAmount" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeMaturityDates" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" order="10400.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsDerivativeFinancialInstrumentsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDerivativeFinancialInstrumentsDerivativeFinancialInstrumentsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsDerivativeFinancialInstrumentsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:type="locator" xlink:label="us-gaap_DerivativeFairValueOfDerivativeLiability" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:type="locator" xlink:label="us-gaap_DerivativeFairValueOfDerivativeAsset" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsPayableMember" xlink:type="locator" xlink:label="us-gaap_AccountsPayableMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AccountsReceivableOtherMember" xlink:type="locator" xlink:label="mdr_AccountsReceivableOtherMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:type="locator" xlink:label="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InformationByFinancialStatementLineItemAxis" xlink:type="locator" xlink:label="us-gaap_InformationByFinancialStatementLineItemAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:type="locator" xlink:label="us-gaap_OtherNoncurrentLiabilitiesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNoncurrentAssetsMember" xlink:type="locator" xlink:label="us-gaap_OtherNoncurrentAssetsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:type="locator" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:type="locator" xlink:label="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativesFairValueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_HedgingDesignationAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_BalanceSheetLocationAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_OtherNoncurrentAssetsMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_OtherNoncurrentLiabilitiesMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_InformationByFinancialStatementLineItemAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InformationByFinancialStatementLineItemAxis" xlink:to="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:to="mdr_AccountsReceivableOtherMember" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FinancialStatementLineItemsWithDifferencesInReportedAmountAndReportingCurrencyDenominatedAmountsDomain" xlink:to="us-gaap_AccountsPayableMember" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DerivativeFairValueOfDerivativeAsset" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DerivativeFairValueOfDerivativeLiability" order="10490.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsEffectsOfDerivativeInstrumentsOnFinancialStatementsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureDerivativeFinancialInstrumentsEffectsOfDerivativeInstrumentsOnFinancialStatementsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureDerivativeFinancialInstrumentsEffectsOfDerivativeInstrumentsOnFinancialStatementsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCurrencyGainLossMember" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyGainLossMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfSalesMember" xlink:type="locator" xlink:label="us-gaap_CostOfSalesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:type="locator" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_HedgingDesignationAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_IncomeStatementLocationAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_CostOfSalesMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_ForeignCurrencyGainLossMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet" order="10340.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFinancialInstrumentsOutstandingMeasuredAtFairValueOnRecurringAndNonrecurringBasisDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureFairValueMeasurementsScheduleOfFinancialInstrumentsOutstandingMeasuredAtFairValueOnRecurringAndNonrecurringBasisDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFinancialInstrumentsOutstandingMeasuredAtFairValueOnRecurringAndNonrecurringBasisDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtFairValue" xlink:type="locator" xlink:label="us-gaap_LongTermDebtFairValue" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestrictedCashAndCashEquivalentsFairValueDisclosure" xlink:type="locator" xlink:label="mdr_RestrictedCashAndCashEquivalentsFairValueDisclosure" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsFairValueDisclosure" />
    <loc xlink:href="mdr-20151231.xsd#mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" xlink:type="locator" xlink:label="mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" />
    <loc xlink:href="mdr-20151231.xsd#mdr_FinancialInstrumentsMeasuredAtFairValueOnRecurringBasisAbstract" xlink:type="locator" xlink:label="mdr_FinancialInstrumentsMeasuredAtFairValueOnRecurringBasisAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:type="locator" xlink:label="us-gaap_EstimateOfFairValueFairValueDisclosureMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember" xlink:type="locator" xlink:label="us-gaap_CarryingReportedAmountFairValueDisclosureMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:type="locator" xlink:label="us-gaap_FairValueDisclosureItemAmountsDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:type="locator" xlink:label="us-gaap_FairValueDisclosureItemAmountsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByMeasurementBasisAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:type="locator" xlink:label="us-gaap_FairValueByBalanceSheetGroupingTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:type="locator" xlink:label="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_FairValueByBalanceSheetGroupingTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_FairValueByMeasurementBasisAxis" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_FairValueDisclosureItemAmountsDomain_2" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_FairValueDisclosureItemAmountsDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueDisclosureItemAmountsDomain" xlink:to="us-gaap_CarryingReportedAmountFairValueDisclosureMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueDisclosureItemAmountsDomain" xlink:to="us-gaap_EstimateOfFairValueFairValueDisclosureMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="mdr_FinancialInstrumentsMeasuredAtFairValueOnRecurringBasisAbstract" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_FinancialInstrumentsMeasuredAtFairValueOnRecurringBasisAbstract" xlink:to="us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" order="10650.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" order="10790.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" xlink:to="us-gaap_CashAndCashEquivalentsFairValueDisclosure" order="10990.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" xlink:to="mdr_RestrictedCashAndCashEquivalentsFairValueDisclosure" order="11150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_FinancialInstrumentsMeasuredAtFairValueOnNonrecurringBasisAbstract" xlink:to="us-gaap_LongTermDebtFairValue" order="11310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_FinancialInstrumentsMeasuredAtFairValueOnRecurringBasisAbstract" xlink:to="us-gaap_DerivativeLiabilities" order="12590.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureFairValueMeasurementsAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureFairValueMeasurementsAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureFairValueMeasurementsAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:type="locator" xlink:label="us-gaap_GoodwillImpairmentLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:type="locator" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" />
    <loc xlink:href="mdr-20151231.xsd#mdr_PropertyPlantAndEquipmentImprovement" xlink:type="locator" xlink:label="mdr_PropertyPlantAndEquipmentImprovement" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets" xlink:type="locator" xlink:label="us-gaap_GainLossOnDispositionOfAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:type="locator" xlink:label="us-gaap_AssetImpairmentCharges" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:type="locator" xlink:label="us-gaap_FairValueByBalanceSheetGroupingTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:type="locator" xlink:label="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_FairValueByBalanceSheetGroupingTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_AssetImpairmentCharges" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_GainLossOnDispositionOfAssets" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="mdr_PropertyPlantAndEquipmentImprovement" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" order="10600.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_GoodwillImpairmentLoss" order="10740.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationTotalStockBasedCompensationExpenseRecognizedDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationTotalStockBasedCompensationExpenseRecognizedDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationTotalStockBasedCompensationExpenseRecognizedDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:type="locator" xlink:label="us-gaap_PerformanceSharesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestrictedStockUnitsAndRestrictedStockMember" xlink:type="locator" xlink:label="mdr_RestrictedStockUnitsAndRestrictedStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="mdr_RestrictedStockUnitsAndRestrictedStockMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense" order="10150.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationTotalGrossUnrecognizedEstimatedCompensationExpenseAndExpectedWeightedAveragePeriodsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationTotalGrossUnrecognizedEstimatedCompensationExpenseAndExpectedWeightedAveragePeriodsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationTotalGrossUnrecognizedEstimatedCompensationExpenseAndExpectedWeightedAveragePeriodsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:type="locator" xlink:label="us-gaap_PerformanceSharesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestrictedStockUnitsAndRestrictedStockMember" xlink:type="locator" xlink:label="mdr_RestrictedStockUnitsAndRestrictedStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="mdr_RestrictedStockUnitsAndRestrictedStockMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" order="10410.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueOfAwardsVested" xlink:type="locator" xlink:label="mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueOfAwardsVested" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CommonStockDividendYield" xlink:type="locator" xlink:label="mdr_CommonStockDividendYield" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:type="locator" xlink:label="us-gaap_PerformanceSharesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LongTermIncentivePlanTwentyZeroNineMember" xlink:type="locator" xlink:label="mdr_LongTermIncentivePlanTwentyZeroNineMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_LongTermIncentivePlanTwentyZeroFourteenMember" xlink:type="locator" xlink:label="mdr_LongTermIncentivePlanTwentyZeroFourteenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="mdr_LongTermIncentivePlanTwentyZeroFourteenMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="mdr_LongTermIncentivePlanTwentyZeroNineMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" order="10540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="mdr_CommonStockDividendYield" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" order="10700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ProceedsFromStockOptionsExercised" order="10820.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions" order="10900.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueOfAwardsVested" order="11060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" order="11210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" order="11360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" order="11400.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationWeightedAverageAssumptionsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationWeightedAverageAssumptionsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationWeightedAverageAssumptionsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="10410.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationNonvestedRestrictedStockRestrictedStockUnitsAndChangesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationNonvestedRestrictedStockRestrictedStockUnitsAndChangesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationNonvestedRestrictedStockRestrictedStockUnitsAndChangesDetail">
    <loc xlink:href="mdr-20151231.xsd#mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValues" xlink:type="locator" xlink:label="mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValues" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <loc xlink:href="mdr-20151231.xsd#mdr_RestrictedStockUnitsAndRestrictedStockMember" xlink:type="locator" xlink:label="mdr_RestrictedStockUnitsAndRestrictedStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="mdr_RestrictedStockUnitsAndRestrictedStockMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" order="10560.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" order="10750.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="10830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" order="10910.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="mdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValues" order="10990.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationNonvestedPerformanceSharesAndPerformanceUnitAwardsAndChangesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockBasedCompensationNonvestedPerformanceSharesAndPerformanceUnitAwardsAndChangesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockBasedCompensationNonvestedPerformanceSharesAndPerformanceUnitAwardsAndChangesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:type="locator" xlink:label="us-gaap_PerformanceSharesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" order="10440.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="10710.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" order="10790.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGrossNoncurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesGrossNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGrossCurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesGrossCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNetNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNetCurrent" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" xlink:type="locator" xlink:label="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesUnrealizedCurrencyTransactionGains" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesUnrealizedCurrencyTransactionGains" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPrepaidExpenses" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesPrepaidExpenses" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesAbstract" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOther" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DeferredTaxAssetsLongTermContracts" xlink:type="locator" xlink:label="mdr_DeferredTaxAssetsLongTermContracts" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DeferredTaxAssetsPension" xlink:type="locator" xlink:label="mdr_DeferredTaxAssetsPension" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsNetAbstract" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNetAbstract" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ReportableEntitiesMember" xlink:type="locator" xlink:label="mdr_ReportableEntitiesMember" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:type="locator" xlink:label="dei_EntityDomain_2" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:type="locator" xlink:label="dei_EntityDomain" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:type="locator" xlink:label="dei_LegalEntityAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ScheduleOfIncomeTaxTable" xlink:type="locator" xlink:label="mdr_ScheduleOfIncomeTaxTable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ScheduleOfIncomeTaxLineItems" xlink:type="locator" xlink:label="mdr_ScheduleOfIncomeTaxLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="mdr_ScheduleOfIncomeTaxLineItems" xlink:to="mdr_ScheduleOfIncomeTaxTable" order="10150.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_ScheduleOfIncomeTaxTable" xlink:to="dei_LegalEntityAxis" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_2" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="mdr_ReportableEntitiesMember" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_ScheduleOfIncomeTaxLineItems" xlink:to="us-gaap_DeferredTaxAssetsNetAbstract" order="10550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="mdr_DeferredTaxAssetsPension" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" order="10710.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" order="10790.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" order="10870.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="mdr_DeferredTaxAssetsLongTermContracts" order="10950.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsOther" order="11030.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsGross" order="11110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance" order="11190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsNet" order="11270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_ScheduleOfIncomeTaxLineItems" xlink:to="us-gaap_DeferredTaxLiabilitiesAbstract" order="11350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" order="11430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesPrepaidExpenses" order="11510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates" order="11590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesUnrealizedCurrencyTransactionGains" order="11670.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredIncomeTaxLiabilities" order="11750.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilities" order="11830.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_ScheduleOfIncomeTaxLineItems" xlink:to="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" order="11910.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DeferredTaxAssetsNetCurrent" order="11990.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DeferredTaxAssetsNetNoncurrent" order="12030.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesGrossCurrent" order="12150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_DeferredTaxAssetAndLiabilitiesAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesGrossNoncurrent" order="12190.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureIncomeTaxesAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries" />
    <loc xlink:href="mdr-20151231.xsd#mdr_UndistributedEarningsLossesRelatedToNoncontrollingInterest" xlink:type="locator" xlink:label="mdr_UndistributedEarningsLossesRelatedToNoncontrollingInterest" />
    <loc xlink:href="mdr-20151231.xsd#mdr_TaxExpenseBenefitOnEarningsIntendToRemit" xlink:type="locator" xlink:label="mdr_TaxExpenseBenefitOnEarningsIntendToRemit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_OperatingLossCarryforwardsValuationAllowance" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OperatingLossCarryforwardsExpirationYear" xlink:type="locator" xlink:label="mdr_OperatingLossCarryforwardsExpirationYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:type="locator" xlink:label="us-gaap_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:type="locator" xlink:label="us-gaap_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:type="locator" xlink:label="us-gaap_StateAndLocalJurisdictionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DomesticCountryMember" xlink:type="locator" xlink:label="us-gaap_DomesticCountryMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForeignCountryMember" xlink:type="locator" xlink:label="us-gaap_ForeignCountryMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ExpirationYearTwoThousandSixteenToTwoThousandEighteenMember" xlink:type="locator" xlink:label="mdr_ExpirationYearTwoThousandSixteenToTwoThousandEighteenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:type="locator" xlink:label="us-gaap_TaxPeriodDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:type="locator" xlink:label="us-gaap_TaxPeriodDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TaxPeriodAxis" xlink:type="locator" xlink:label="us-gaap_TaxPeriodAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:type="locator" xlink:label="us-gaap_OperatingLossCarryforwardsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:type="locator" xlink:label="us-gaap_OperatingLossCarryforwardsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_OperatingLossCarryforwardsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_OperatingLossCarryforwardsTable" xlink:to="us-gaap_TaxPeriodAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TaxPeriodAxis" xlink:to="us-gaap_TaxPeriodDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TaxPeriodAxis" xlink:to="us-gaap_TaxPeriodDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TaxPeriodDomain" xlink:to="mdr_ExpirationYearTwoThousandSixteenToTwoThousandEighteenMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_OperatingLossCarryforwardsTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_OperatingLossCarryforwardsTable" xlink:to="us-gaap_IncomeTaxAuthorityAxis" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain_2" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_ForeignCountryMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_DomesticCountryMember" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_StateAndLocalJurisdictionMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_OperatingLossCarryforwardsTable" xlink:to="us-gaap_RangeAxis" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance" order="10540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="mdr_OperatingLossCarryforwardsExpirationYear" order="10730.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_OperatingLossCarryforwardsValuationAllowance" order="10850.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic" order="10910.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal" order="11210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="mdr_TaxExpenseBenefitOnEarningsIntendToRemit" order="11480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="mdr_UndistributedEarningsLossesRelatedToNoncontrollingInterest" order="11540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries" order="11600.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" order="11690.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureEarningsPerShareAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureEarningsPerShareAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureEarningsPerShareAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EarningsPerShareTable" xlink:type="locator" xlink:label="mdr_EarningsPerShareTable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_EarningsPerShareLineItems" xlink:type="locator" xlink:label="mdr_EarningsPerShareLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="mdr_EarningsPerShareLineItems" xlink:to="mdr_EarningsPerShareTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_EarningsPerShareTable" xlink:to="us-gaap_AwardTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockUnitsRSUMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_EarningsPerShareLineItems" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_EarningsPerShareLineItems" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="10260.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockholderSEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossReclassifiedDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureStockholderSEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossReclassifiedDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureStockholderSEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossReclassifiedDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:type="locator" xlink:label="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedTranslationAdjustmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" order="10030.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedTranslationAdjustmentMember" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" order="10690.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LeaseAndRentalExpense" xlink:type="locator" xlink:label="us-gaap_LeaseAndRentalExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_LossContingencyAccrualAtCarryingValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss" xlink:type="locator" xlink:label="us-gaap_LossContingencyEstimateOfPossibleLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent" xlink:type="locator" xlink:label="us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyDomicileOfLitigation" xlink:type="locator" xlink:label="us-gaap_LossContingencyDomicileOfLitigation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationSettlementAmount" xlink:type="locator" xlink:label="us-gaap_LitigationSettlementAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:type="locator" xlink:label="us-gaap_LossContingencyDamagesSoughtValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:type="locator" xlink:label="us-gaap_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:type="locator" xlink:label="us-gaap_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:type="locator" xlink:label="us-gaap_RangeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AtlanticTiburonOnePteLtdMember" xlink:type="locator" xlink:label="mdr_AtlanticTiburonOnePteLtdMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:type="locator" xlink:label="us-gaap_LitigationCaseTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:type="locator" xlink:label="us-gaap_LitigationCaseTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationCaseAxis" xlink:type="locator" xlink:label="us-gaap_LitigationCaseAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesTable" xlink:type="locator" xlink:label="us-gaap_LossContingenciesTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:type="locator" xlink:label="us-gaap_LossContingenciesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingenciesTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LossContingenciesTable" xlink:to="us-gaap_LitigationCaseAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LitigationCaseAxis" xlink:to="us-gaap_LitigationCaseTypeDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LitigationCaseAxis" xlink:to="us-gaap_LitigationCaseTypeDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LitigationCaseTypeDomain" xlink:to="mdr_AtlanticTiburonOnePteLtdMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LossContingenciesTable" xlink:to="us-gaap_RangeAxis" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingencyDamagesSoughtValue" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LitigationSettlementAmount" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingencyDomicileOfLitigation" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingencyEstimateOfPossibleLoss" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingencyAccrualAtCarryingValue" order="10540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LeaseAndRentalExpense" order="10610.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAcquisitionsAdditionalInformationDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureAcquisitionsAdditionalInformationDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureAcquisitionsAdditionalInformationDetail">
    <loc xlink:href="mdr-20151231.xsd#mdr_IncreaseDecreaseInEquityMethodInvestment" xlink:type="locator" xlink:label="mdr_IncreaseDecreaseInEquityMethodInvestment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapital" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityMethodInvestmentSummarizedFinancialInformationMinorityInterest" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationMinorityInterest" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfBusinessesAcquired" xlink:type="locator" xlink:label="us-gaap_NumberOfBusinessesAcquired" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" xlink:type="locator" xlink:label="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinorityInterestPeriodIncreaseDecrease" xlink:type="locator" xlink:label="us-gaap_MinorityInterestPeriodIncreaseDecrease" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" />
    <loc xlink:href="mdr-20151231.xsd#mdr_BerlianMcDermottSdnBhdMember" xlink:type="locator" xlink:label="mdr_BerlianMcDermottSdnBhdMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_THHEMember" xlink:type="locator" xlink:label="mdr_THHEMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_DeepseaGroupLimitedMember" xlink:type="locator" xlink:label="mdr_DeepseaGroupLimitedMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OceanteamASAMember" xlink:type="locator" xlink:label="mdr_OceanteamASAMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_BusinessAcquisitionAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="mdr_OceanteamASAMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_AwardTypeAxis" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="mdr_DeepseaGroupLimitedMember" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="mdr_THHEMember" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="mdr_BerlianMcDermottSdnBhdMember" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_PaymentsToAcquireBusinessesGross" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_MinorityInterestPeriodIncreaseDecrease" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="mdr_AdjustmentsToAdditionalPaidInCapitalCommonStockPayableForPrepaidService" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessCombinationConsiderationTransferred1" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" order="10650.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_NumberOfBusinessesAcquired" order="10720.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_EquityMethodInvestments" order="10940.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationMinorityInterest" order="11040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_AdditionalPaidInCapital" order="11140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="mdr_IncreaseDecreaseInEquityMethodInvestment" order="11240.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutOperationsInDifferentSegmentsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureSegmentReportingInformationAboutOperationsInDifferentSegmentsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutOperationsInDifferentSegmentsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentForAmortization" xlink:type="locator" xlink:label="us-gaap_AdjustmentForAmortization" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationAndAmortization" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:type="locator" xlink:label="us-gaap_Revenues" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:type="locator" xlink:label="us-gaap_CorporateNonSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConsolidationItemsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConsolidationItemsAxis" xlink:to="us-gaap_ConsolidationItemsDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_CorporateNonSegmentMember" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10490.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_Revenues" order="10780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_OperatingIncomeLoss" order="11200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" order="11720.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_DepreciationAndAmortization" order="12260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_AdjustmentForAmortization" order="12800.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingSignificantImpactOfCustomersOnCompanySegmentsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureSegmentReportingSignificantImpactOfCustomersOnCompanySegmentsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingSignificantImpactOfCustomersOnCompanySegmentsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskPercentage1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:type="locator" xlink:label="us-gaap_SalesRevenueNetMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AzerbaijanInternationalOilCompanyMember" xlink:type="locator" xlink:label="mdr_AzerbaijanInternationalOilCompanyMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_SaudiAramcoMember" xlink:type="locator" xlink:label="mdr_SaudiAramcoMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_InpexOperationsAustraliaPtyLtdMember" xlink:type="locator" xlink:label="mdr_InpexOperationsAustraliaPtyLtdMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:type="locator" xlink:label="us-gaap_NameOfMajorCustomerDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:type="locator" xlink:label="us-gaap_NameOfMajorCustomerDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:type="locator" xlink:label="us-gaap_MajorCustomersAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MiddleEastMember" xlink:type="locator" xlink:label="us-gaap_MiddleEastMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AsiaMember" xlink:type="locator" xlink:label="us-gaap_AsiaMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:type="locator" xlink:label="us-gaap_StatementGeographicalAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:type="locator" xlink:label="us-gaap_CustomerConcentrationRiskMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConcentrationRiskByTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain_2" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_CustomerConcentrationRiskMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_StatementGeographicalAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="us-gaap_AsiaMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="us-gaap_MiddleEastMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_MajorCustomersAxis" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorCustomersAxis" xlink:to="us-gaap_NameOfMajorCustomerDomain_2" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorCustomersAxis" xlink:to="us-gaap_NameOfMajorCustomerDomain" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NameOfMajorCustomerDomain" xlink:to="mdr_InpexOperationsAustraliaPtyLtdMember" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NameOfMajorCustomerDomain" xlink:to="mdr_SaudiAramcoMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NameOfMajorCustomerDomain" xlink:to="mdr_AzerbaijanInternationalOilCompanyMember" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_2" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_SalesRevenueNetMember" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ConcentrationRiskPercentage1" order="10560.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutServiceLinesAndOperationsInDifferentGeographicAreasDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureSegmentReportingInformationAboutServiceLinesAndOperationsInDifferentGeographicAreasDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutServiceLinesAndOperationsInDifferentGeographicAreasDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:type="locator" xlink:label="us-gaap_Revenues" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ProcurementActivitiesMember" xlink:type="locator" xlink:label="mdr_ProcurementActivitiesMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ProjectServicesAndEngineeringOperationsMember" xlink:type="locator" xlink:label="mdr_ProjectServicesAndEngineeringOperationsMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_FabricationFacilityMember" xlink:type="locator" xlink:label="mdr_FabricationFacilityMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_InstallationOperationsMember" xlink:type="locator" xlink:label="mdr_InstallationOperationsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:type="locator" xlink:label="us-gaap_ProductsAndServicesDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:type="locator" xlink:label="us-gaap_ProductsAndServicesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:type="locator" xlink:label="us-gaap_ProductOrServiceAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherCountriesMember" xlink:type="locator" xlink:label="mdr_OtherCountriesMember" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_MY" xlink:type="locator" xlink:label="country_MY" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_AZ" xlink:type="locator" xlink:label="country_AZ" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:type="locator" xlink:label="country_US" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_QA" xlink:type="locator" xlink:label="country_QA" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_ID" xlink:type="locator" xlink:label="country_ID" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_BR" xlink:type="locator" xlink:label="country_BR" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_AE" xlink:type="locator" xlink:label="country_AE" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_BN" xlink:type="locator" xlink:label="country_BN" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_MX" xlink:type="locator" xlink:label="country_MX" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_SA" xlink:type="locator" xlink:label="country_SA" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_AU" xlink:type="locator" xlink:label="country_AU" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:type="locator" xlink:label="us-gaap_StatementGeographicalAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:type="locator" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingRevenueReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementGeographicalAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_AU" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_SA" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_MX" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_BN" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_AE" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_BR" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_ID" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_QA" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_US" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_AZ" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_MY" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="mdr_OtherCountriesMember" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:to="us-gaap_ProductOrServiceAxis" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ProductOrServiceAxis" xlink:to="us-gaap_ProductsAndServicesDomain_2" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ProductOrServiceAxis" xlink:to="us-gaap_ProductsAndServicesDomain" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProductsAndServicesDomain" xlink:to="mdr_InstallationOperationsMember" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProductsAndServicesDomain" xlink:to="mdr_FabricationFacilityMember" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProductsAndServicesDomain" xlink:to="mdr_ProjectServicesAndEngineeringOperationsMember" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ProductsAndServicesDomain" xlink:to="mdr_ProcurementActivitiesMember" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:to="us-gaap_Revenues" order="10440.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutSegmentAssetsAndPropertyPlantAndEquipmentByCountryDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureSegmentReportingInformationAboutSegmentAssetsAndPropertyPlantAndEquipmentByCountryDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutSegmentAssetsAndPropertyPlantAndEquipmentByCountryDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Assets" xlink:type="locator" xlink:label="us-gaap_Assets" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AssetsContinuingOperations" xlink:type="locator" xlink:label="mdr_AssetsContinuingOperations" />
    <loc xlink:href="mdr-20151231.xsd#mdr_OtherCountriesMember" xlink:type="locator" xlink:label="mdr_OtherCountriesMember" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_ES" xlink:type="locator" xlink:label="country_ES" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_SG" xlink:type="locator" xlink:label="country_SG" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_SA" xlink:type="locator" xlink:label="country_SA" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_BR" xlink:type="locator" xlink:label="country_BR" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_MY" xlink:type="locator" xlink:label="country_MY" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_MX" xlink:type="locator" xlink:label="country_MX" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_AE" xlink:type="locator" xlink:label="country_AE" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_ID" xlink:type="locator" xlink:label="country_ID" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:type="locator" xlink:label="country_US" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:type="locator" xlink:label="us-gaap_StatementGeographicalAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_CorporateAndOtherNonSegmentMember" xlink:type="locator" xlink:label="mdr_CorporateAndOtherNonSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" order="10050.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConsolidationItemsAxis" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConsolidationItemsAxis" xlink:to="us-gaap_ConsolidationItemsDomain" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="mdr_CorporateAndOtherNonSegmentMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_StatementGeographicalAxis" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_US" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_ID" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_AE" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_MX" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_MY" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_BR" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_SA" order="10440.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_SG" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="country_ES" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="mdr_OtherCountriesMember" order="10500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="mdr_AssetsContinuingOperations" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_Assets" order="11010.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="11090.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutUnconsolidatedAffiliatesDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureSegmentReportingInformationAboutUnconsolidatedAffiliatesDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureSegmentReportingInformationAboutUnconsolidatedAffiliatesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AsiaSegmentMember" xlink:type="locator" xlink:label="mdr_AsiaSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="mdr-20151231.xsd#mdr_AmericasEuropeAndAfricaSegmentMember" xlink:type="locator" xlink:label="mdr_AmericasEuropeAndAfricaSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:type="locator" xlink:label="us-gaap_CorporateNonSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:type="locator" xlink:label="us-gaap_ConsolidationItemsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:type="locator" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="us-gaap_ConsolidationItemsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConsolidationItemsAxis" xlink:to="us-gaap_ConsolidationItemsDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConsolidationItemsDomain" xlink:to="us-gaap_CorporateNonSegmentMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AmericasEuropeAndAfricaSegmentMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_AsiaSegmentMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_EquityMethodInvestments" order="10760.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureQuarterlyFinancialDataUnauditedSelectedUnauditedQuarterlyFinancialInformationParentheticalDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureQuarterlyFinancialDataUnauditedSelectedUnauditedQuarterlyFinancialInformationParentheticalDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureQuarterlyFinancialDataUnauditedSelectedUnauditedQuarterlyFinancialInformationParentheticalDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:type="locator" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss" />
    <loc xlink:href="mdr-20151231.xsd#mdr_HarborIslandFacilityMember" xlink:type="locator" xlink:label="mdr_HarborIslandFacilityMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AmericasMember" xlink:type="locator" xlink:label="us-gaap_AmericasMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:type="locator" xlink:label="us-gaap_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:type="locator" xlink:label="us-gaap_StatementGeographicalAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_MiddleEastSegmentMember" xlink:type="locator" xlink:label="mdr_MiddleEastSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="mdr-20151231.xsd#mdr_QuarterlyFinancialInformationTable" xlink:type="locator" xlink:label="mdr_QuarterlyFinancialInformationTable" />
    <loc xlink:href="mdr-20151231.xsd#mdr_QuarterlyFinancialInformationLineItems" xlink:type="locator" xlink:label="mdr_QuarterlyFinancialInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="mdr_QuarterlyFinancialInformationLineItems" xlink:to="mdr_QuarterlyFinancialInformationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_QuarterlyFinancialInformationTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_MiddleEastSegmentMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="mdr_QuarterlyFinancialInformationTable" xlink:to="us-gaap_StatementGeographicalAxis" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementGeographicalAxis" xlink:to="us-gaap_SegmentGeographicalDomain" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentGeographicalDomain" xlink:to="us-gaap_AmericasMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="mdr_HarborIslandFacilityMember" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_QuarterlyFinancialInformationLineItems" xlink:to="us-gaap_DefinedBenefitPlanActuarialGainLoss" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="mdr_QuarterlyFinancialInformationLineItems" xlink:to="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" order="10280.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureValuationAndQualifyingAccountsDetail" xlink:href="mdr-20151231.xsd#Role_DisclosureValuationAndQualifyingAccountsDetail" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.mcdermott.com/20151231/taxonomy/role/DisclosureValuationAndQualifyingAccountsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesRecoveries" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesRecoveries" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDeductions" />
    <loc xlink:href="mdr-20151231.xsd#mdr_ValuationAllowancesAndReservesChargedToRecoveredFromOtherAccounts" xlink:type="locator" xlink:label="mdr_ValuationAllowancesAndReservesChargedToRecoveredFromOtherAccounts" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesBalance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsMember" xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:type="locator" xlink:label="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureTable" xlink:type="locator" xlink:label="us-gaap_ValuationAndQualifyingAccountsDisclosureTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="us-gaap_ValuationAndQualifyingAccountsDisclosureTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureTable" xlink:to="us-gaap_ValuationAllowancesAndReservesTypeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="us-gaap_ValuationAllowancesAndReservesDomain" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" order="10080.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="us-gaap_AllowanceForDoubtfulAccountsMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="us-gaap_ValuationAllowancesAndReservesBalance" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="mdr_ValuationAllowancesAndReservesChargedToRecoveredFromOtherAccounts" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="us-gaap_ValuationAllowancesAndReservesDeductions" order="10600.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="us-gaap_ValuationAllowancesAndReservesRecoveries" order="10660.00" priority="2" use="optional" />
  </definitionLink>
</linkbase>


