<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 5.2a -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: http://www.novaworks.co -->
    <!-- Field: Doc-Info; Name: Source; Value: GnbtS%2D1.xfr; Date: 2020%2D02%2D14T20:35:18Z -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x80130002 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef roleURI="http://generex.com/role/DocumentAndEntityInformation" xlink:href="gnbt-20191031.xsd#DocumentAndEntityInformation" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/ConsolidatedBalanceSheets" xlink:href="gnbt-20191031.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="gnbt-20191031.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveLossIncome" xlink:href="gnbt-20191031.xsd#ConsolidatedStatementsOfOperationsAndComprehensiveLossIncome" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Statement-ConsolidatedStatementsOfChangesInStockholdersEquity" xlink:href="gnbt-20191031.xsd#Statement-ConsolidatedStatementsOfChangesInStockholdersEquity" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="gnbt-20191031.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/OrganizationAndBusiness" xlink:href="gnbt-20191031.xsd#OrganizationAndBusiness" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="gnbt-20191031.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/LoanFromRelatedParties" xlink:href="gnbt-20191031.xsd#LoanFromRelatedParties" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/CommitmentsAndContingencies" xlink:href="gnbt-20191031.xsd#CommitmentsAndContingencies" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Leases" xlink:href="gnbt-20191031.xsd#Leases" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/PropertyAndEquipment" xlink:href="gnbt-20191031.xsd#PropertyAndEquipment" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/StockholdersEquity" xlink:href="gnbt-20191031.xsd#StockholdersEquity" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/RedeemableNon-controllingInterest" xlink:href="gnbt-20191031.xsd#RedeemableNon-controllingInterest" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Inventory" xlink:href="gnbt-20191031.xsd#Inventory" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NotesPayable" xlink:href="gnbt-20191031.xsd#NotesPayable" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/IncomeTaxes" xlink:href="gnbt-20191031.xsd#IncomeTaxes" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NetIncomePerShareEps" xlink:href="gnbt-20191031.xsd#NetIncomePerShareEps" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssets" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions" xlink:href="gnbt-20191031.xsd#Acquisitions" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/DerivativeLiability" xlink:href="gnbt-20191031.xsd#DerivativeLiability" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Warrants" xlink:href="gnbt-20191031.xsd#Warrants" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Stock-basedCompensation" xlink:href="gnbt-20191031.xsd#Stock-basedCompensation" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SubsequentEvents" xlink:href="gnbt-20191031.xsd#SubsequentEvents" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="gnbt-20191031.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="gnbt-20191031.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/LeasesTables" xlink:href="gnbt-20191031.xsd#LeasesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/PropertyAndEquipmentTables" xlink:href="gnbt-20191031.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/InventoryTables" xlink:href="gnbt-20191031.xsd#InventoryTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/IncomeTaxesTables" xlink:href="gnbt-20191031.xsd#IncomeTaxesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NetIncomePerShareEpsTables" xlink:href="gnbt-20191031.xsd#NetIncomePerShareEpsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/AcquisitionsTables" xlink:href="gnbt-20191031.xsd#AcquisitionsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/DerivativeLiabilityTables" xlink:href="gnbt-20191031.xsd#DerivativeLiabilityTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/WarrantsTables" xlink:href="gnbt-20191031.xsd#WarrantsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Stock-basedCompensationTables" xlink:href="gnbt-20191031.xsd#Stock-basedCompensationTables" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/OrganizationOfBusinessAndGoingConcernDetailsNarrative" xlink:href="gnbt-20191031.xsd#OrganizationOfBusinessAndGoingConcernDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="gnbt-20191031.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:href="gnbt-20191031.xsd#SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/LoanFromRelatedPartiesDetailsNarrative" xlink:href="gnbt-20191031.xsd#LoanFromRelatedPartiesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:href="gnbt-20191031.xsd#CommitmentsAndContingenciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/LeasesDetails" xlink:href="gnbt-20191031.xsd#LeasesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/LeasesDetailsNarrative" xlink:href="gnbt-20191031.xsd#LeasesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/PropertyAndEquipmentDetails" xlink:href="gnbt-20191031.xsd#PropertyAndEquipmentDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/PropertyAndEquipmentDetailsNarrative" xlink:href="gnbt-20191031.xsd#PropertyAndEquipmentDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/StockholdersEquityDetailsNarrative" xlink:href="gnbt-20191031.xsd#StockholdersEquityDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/RedeemableNon-controllingInterestDetailsNarrative" xlink:href="gnbt-20191031.xsd#RedeemableNon-controllingInterestDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/InventoryDetails" xlink:href="gnbt-20191031.xsd#InventoryDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NotesPayableDetailsNarrative" xlink:href="gnbt-20191031.xsd#NotesPayableDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/IncomeTaxes-DeferredIncomeTaxesDetails" xlink:href="gnbt-20191031.xsd#IncomeTaxes-DeferredIncomeTaxesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/IncomeTaxes-ReconciliationOfEffectiveTaxRateDetails" xlink:href="gnbt-20191031.xsd#IncomeTaxes-ReconciliationOfEffectiveTaxRateDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/IncomeTaxesDetailsNarrative" xlink:href="gnbt-20191031.xsd#IncomeTaxesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NetLossIncomePerShareEps-ComputationOfDilutedEpsDetails" xlink:href="gnbt-20191031.xsd#NetLossIncomePerShareEps-ComputationOfDilutedEpsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/NetIncomePerShareEps-ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareDetails" xlink:href="gnbt-20191031.xsd#NetIncomePerShareEps-ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssetsEstimatedAmortizationExpenseDetails" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssetsEstimatedAmortizationExpenseDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssetsChangesInValueOfGoodwillDetails" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssetsChangesInValueOfGoodwillDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/GoodwillAndIntangibleAssetsDetailsNarrative" xlink:href="gnbt-20191031.xsd#GoodwillAndIntangibleAssetsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-NetPurchasePriceOfNgdxDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-NetPurchasePriceOfNgdxDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-FairValueAssumptionsUsedInAccountingForWarrantsDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-FairValueAssumptionsUsedInAccountingForWarrantsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-FairValueAssumptionsUsedInAccountingForCallOptionsDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-FairValueAssumptionsUsedInAccountingForCallOptionsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-PurchasePriceAllocatedAsOfAcquisitionDateDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-PurchasePriceAllocatedAsOfAcquisitionDateDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-SummaryOfAcquisitionDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-SummaryOfAcquisitionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-FairValueOfMedisourceAcquisitionDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-FairValueOfMedisourceAcquisitionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-FairValueOfPantheonAcquisitionDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-FairValueOfPantheonAcquisitionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-EstimatedAmortizationExpenseDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-EstimatedAmortizationExpenseDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-PurchasePriceAsOfRegentysAcquisitionDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-PurchasePriceAsOfRegentysAcquisitionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-PurchasePriceAsOfOlaregenAcquisitionDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-PurchasePriceAsOfOlaregenAcquisitionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-IntangibleAssetsDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-IntangibleAssetsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Acquisitions-UnauditedSupplementalProFormaDataDetails" xlink:href="gnbt-20191031.xsd#Acquisitions-UnauditedSupplementalProFormaDataDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/AcquisitionsDetailsNarrative" xlink:href="gnbt-20191031.xsd#AcquisitionsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/DerivativeLiabilityDetails" xlink:href="gnbt-20191031.xsd#DerivativeLiabilityDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/WarrantsDetails" xlink:href="gnbt-20191031.xsd#WarrantsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/WarrantsDetailsNarrative" xlink:href="gnbt-20191031.xsd#WarrantsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Stock-basedCompensation-CommonStockOptionsGrantedForfeitedOrExpiredAndExercisedDetails" xlink:href="gnbt-20191031.xsd#Stock-basedCompensation-CommonStockOptionsGrantedForfeitedOrExpiredAndExercisedDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Stock-basedCompensation-FairValueAssumptionsUsedInBlack-scholesOption-pricingDetails" xlink:href="gnbt-20191031.xsd#Stock-basedCompensation-FairValueAssumptionsUsedInBlack-scholesOption-pricingDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/Stock-basedCompensationDetailsNarrative" xlink:href="gnbt-20191031.xsd#Stock-basedCompensationDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://generex.com/role/SubsequentEventsDetailsNarrative" xlink:href="gnbt-20191031.xsd#SubsequentEventsDetailsNarrative" xlink:type="simple" />
    <link: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" />
    <link: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" />
    <link: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" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link: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" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/DocumentAndEntityInformation" xlink:title="00000001 - Document - Document and Entity Information" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/ConsolidatedBalanceSheets" xlink:title="00000002 - Statement - CONSOLIDATED BALANCE SHEETS">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeriesHPreferredStockMember" xlink:label="loc_us-gaapSeriesHPreferredStockMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesHPreferredStockMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SeriesIPreferredStockMember" xlink:label="loc_GNBTSeriesIPreferredStockMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_GNBTSeriesIPreferredStockMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaapAssetsAbstract_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAssetsAbstract_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaapAssetsCurrentAbstract_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapAssetsCurrentAbstract_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNet" xlink:label="loc_us-gaapAccountsReceivableNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapAccountsReceivableNet_80" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapInventoryNet_80" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapOtherAssetsCurrent_80" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapAssetsCurrent_80" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_80" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CallOptions" xlink:label="loc_GNBTCallOptions_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_GNBTCallOptions_80" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapGoodwill_80" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsNet_80" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset_80" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssets" xlink:label="loc_us-gaapOtherAssets_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapOtherAssets_80" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_80" xlink:to="loc_us-gaapAssets_80" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaapLiabilitiesCurrentAbstract_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapLiabilitiesCurrentAbstract_80" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_80" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapNotesPayable_80" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LoansFromRelatedParties" xlink:label="loc_GNBTLoansFromRelatedParties_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_GNBTLoansFromRelatedParties_80" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapOperatingLeaseLiabilityCurrent_80" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesCurrent" xlink:label="loc_us-gaapDeferredTaxLiabilitiesCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapDeferredTaxLiabilitiesCurrent_80" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapLiabilitiesCurrent_80" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="loc_us-gaapDerivativeLiabilitiesNoncurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapDerivativeLiabilitiesNoncurrent_80" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayableNoncurrent" xlink:label="loc_GNBTCommonStockPayableNoncurrent_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_GNBTCommonStockPayableNoncurrent_80" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WarrantsToBeIssued" xlink:label="loc_GNBTWarrantsToBeIssued_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_GNBTWarrantsToBeIssued_80" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapLiabilities_80" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="loc_us-gaapRedeemableNoncontrollingInterestEquityCarryingAmount_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapRedeemableNoncontrollingInterestEquityCarryingAmount_80" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaapStockholdersEquityAbstract_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapStockholdersEquityAbstract_80" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaapPreferredStockValue_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapPreferredStockValue_80" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapCommonStockValue_80" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayable" xlink:label="loc_GNBTCommonStockPayable_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_GNBTCommonStockPayable_80" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaapAdditionalPaidInCapitalCommonStock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapAdditionalPaidInCapitalCommonStock_80" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit_80" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax_80" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaapMinorityInterest_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapMinorityInterest_80" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_80" xlink:to="loc_us-gaapStockholdersEquity_80" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_80" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquity_80" xlink:type="arc" order="36" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:title="00000003 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeriesHPreferredStockMember" xlink:label="loc_us-gaapSeriesHPreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesHPreferredStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SeriesIPreferredStockMember" xlink:label="loc_GNBTSeriesIPreferredStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_GNBTSeriesIPreferredStockMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaapPreferredStockSharesAuthorized_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesAuthorized_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_80" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaapCommonStockSharesAuthorized_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesAuthorized_80" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesIssued_80" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaapCommonStockSharesOutstanding_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesOutstanding_80" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveLossIncome" xlink:title="00000004 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Statement-ConsolidatedStatementsOfChangesInStockholdersEquity" xlink:title="00000005 - Statement - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS&apos; EQUITY">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaapPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapPreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayableMember" xlink:label="loc_GNBTCommonStockPayableMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_GNBTCommonStockPayableMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaapAdditionalPaidInCapitalMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAdditionalPaidInCapitalMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaapRetainedEarningsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapRetainedEarningsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SubTotalMember" xlink:label="loc_GNBTSubTotalMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_GNBTSubTotalMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaapNoncontrollingInterestMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapNoncontrollingInterestMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockholdersEquity_100" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaapSharesOutstanding_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesOutstanding_100" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InvestmentInSubsidiaryByNoncontrollingInterests" xlink:label="loc_GNBTInvestmentInSubsidiaryByNoncontrollingInterests_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInvestmentInSubsidiaryByNoncontrollingInterests_100" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfPreferredSeriesH" xlink:label="loc_GNBTConversionOfPreferredSeriesH_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfPreferredSeriesH_100" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfPreferredSeriesHInShares" xlink:label="loc_GNBTConversionOfPreferredSeriesHInShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfPreferredSeriesHInShares_100" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfPreferredSeriesI" xlink:label="loc_GNBTConversionOfPreferredSeriesI_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfPreferredSeriesI_100" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfPreferredSeriesIInShares" xlink:label="loc_GNBTConversionOfPreferredSeriesIInShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfPreferredSeriesIInShares_100" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ExerciseOfCallOptionToAcquireNoncontrollingInterest" xlink:label="loc_GNBTExerciseOfCallOptionToAcquireNoncontrollingInterest_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTExerciseOfCallOptionToAcquireNoncontrollingInterest_100" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_100" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_IssuanceOfCommonStockPayable" xlink:label="loc_GNBTIssuanceOfCommonStockPayable_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTIssuanceOfCommonStockPayable_100" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_IssuanceOfCommonStockPayableShares" xlink:label="loc_GNBTIssuanceOfCommonStockPayableShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTIssuanceOfCommonStockPayableShares_100" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfDebtToEquity" xlink:label="loc_GNBTConversionOfDebtToEquity_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfDebtToEquity_100" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConversionOfDebtToEquityInShares" xlink:label="loc_GNBTConversionOfDebtToEquityInShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConversionOfDebtToEquityInShares_100" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueStockOptionsExercised_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueStockOptionsExercised_100" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_100" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_100" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AntigenDividend" xlink:label="loc_GNBTAntigenDividend_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAntigenDividend_100" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromIssuanceOfWarrants" xlink:label="loc_us-gaapProceedsFromIssuanceOfWarrants_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfWarrants_100" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AcquisitionOfNciOfRegentys" xlink:label="loc_GNBTAcquisitionOfNciOfRegentys_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAcquisitionOfNciOfRegentys_100" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AcquisitionOfNciOfOlaregen" xlink:label="loc_GNBTAcquisitionOfNciOfOlaregen_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAcquisitionOfNciOfOlaregen_100" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AcquisitionOfOlaregenSeriesPreferredStock" xlink:label="loc_GNBTAcquisitionOfOlaregenSeriesPreferredStock_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAcquisitionOfOlaregenSeriesPreferredStock_100" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ReclassificationOfEquityToLiability" xlink:label="loc_GNBTReclassificationOfEquityToLiability_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTReclassificationOfEquityToLiability_100" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ExtinguishmentOfDerivativeLiabilityAssociatedWithConvertibleNotes" xlink:label="loc_GNBTExtinguishmentOfDerivativeLiabilityAssociatedWithConvertibleNotes_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTExtinguishmentOfDerivativeLiabilityAssociatedWithConvertibleNotes_100" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueAcquisitions_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueAcquisitions_100" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_100" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ReductionOfDerivativeLiability" xlink:label="loc_GNBTReductionOfDerivativeLiability_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTReductionOfDerivativeLiability_100" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CancellationOfShares" xlink:label="loc_GNBTCancellationOfShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCancellationOfShares_100" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CancellationOfSharesInShares" xlink:label="loc_GNBTCancellationOfSharesInShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCancellationOfSharesInShares_100" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PurchaseOfSharesInSubsidiary" xlink:label="loc_GNBTPurchaseOfSharesInSubsidiary_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPurchaseOfSharesInSubsidiary_100" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TranslationAdjustmentFunctionalToReportingCurrencyIncreaseDecreaseGrossOfTax" xlink:label="loc_us-gaapTranslationAdjustmentFunctionalToReportingCurrencyIncreaseDecreaseGrossOfTax_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTranslationAdjustmentFunctionalToReportingCurrencyIncreaseDecreaseGrossOfTax_100" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLoss_100" xlink:type="arc" order="31" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/ConsolidatedStatementsOfCashFlows" xlink:title="00000006 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/OrganizationAndBusiness" xlink:title="00000007 - Disclosure - Organization of Business and Going Concern" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SummaryOfSignificantAccountingPolicies" xlink:title="00000008 - Disclosure - Summary of Significant Accounting Policies" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/LoanFromRelatedParties" xlink:title="00000009 - Disclosure - Loans from Related Parties" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/CommitmentsAndContingencies" xlink:title="00000010 - Disclosure - Commitments and Contingencies" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Leases" xlink:title="00000011 - Disclosure - Leases" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/PropertyAndEquipment" xlink:title="00000012 - Disclosure - Property and Equipment" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/StockholdersEquity" xlink:title="00000013 - Disclosure - Stockholders&apos; Equity" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/RedeemableNon-controllingInterest" xlink:title="00000014 - Disclosure - Redeemable Non-Controlling Interest" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Inventory" xlink:title="00000015 - Disclosure - Inventory" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NotesPayable" xlink:title="00000016 - Disclosure - Notes Payable" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/IncomeTaxes" xlink:title="00000017 - Disclosure - Income Taxes" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NetIncomePerShareEps" xlink:title="00000018 - Disclosure - Net Income Per Share (EPS)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssets" xlink:title="00000019 - Disclosure - Goodwill and Intangible Assets" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions" xlink:title="00000020 - Disclosure - Acquisitions" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/DerivativeLiability" xlink:title="00000021 - Disclosure - Derivative Liability" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Warrants" xlink:title="00000022 - Disclosure - Warrants" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Stock-basedCompensation" xlink:title="00000023 - Disclosure - Stock-Based Compensation" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SubsequentEvents" xlink:title="00000024 - Disclosure - Subsequent Events" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:title="00000025 - Disclosure - Summary of Significant Accounting Policies (Policies)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:title="00000026 - Disclosure - Summary of Significant Accounting Policies (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/LeasesTables" xlink:title="00000027 - Disclosure - Leases (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/PropertyAndEquipmentTables" xlink:title="00000028 - Disclosure - Property and Equipment (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/InventoryTables" xlink:title="00000029 - Disclosure - Inventory (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/IncomeTaxesTables" xlink:title="00000030 - Disclosure - Income Taxes (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NetIncomePerShareEpsTables" xlink:title="00000031 - Disclosure - Net Income Per Share (EPS) (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssetsTables" xlink:title="00000032 - Disclosure - Goodwill and Intangible Assets (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/AcquisitionsTables" xlink:title="00000033 - Disclosure - Acquisitions (Tables)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MedisourceMember" xlink:label="loc_GNBTMedisourceMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTMedisourceMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PantheonMember" xlink:label="loc_GNBTPantheonMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPantheonMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoMember" xlink:label="loc_GNBTVenetoMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRegentysMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTableTextBlock" xlink:label="loc_us-gaapBusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTableTextBlock_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FairValueAssumptionsUsedInAccountingForWarrantsTableTextBlock" xlink:label="loc_GNBTFairValueAssumptionsUsedInAccountingForWarrantsTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTFairValueAssumptionsUsedInAccountingForWarrantsTableTextBlock_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FairValueAssumptionsUsedInAccountingForCallOptionsTableTextBlock" xlink:label="loc_GNBTFairValueAssumptionsUsedInAccountingForCallOptionsTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTFairValueAssumptionsUsedInAccountingForCallOptionsTableTextBlock_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PurchasePriceAllocatedAsOfAcquisitionDateTableTextBlock" xlink:label="loc_GNBTPurchasePriceAllocatedAsOfAcquisitionDateTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPurchasePriceAllocatedAsOfAcquisitionDateTableTextBlock_80" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SummaryOfAcquisitionTableTextBlock" xlink:label="loc_GNBTSummaryOfAcquisitionTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTSummaryOfAcquisitionTableTextBlock_80" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_EstimatedAmortizationExpenseTableTextBlock" xlink:label="loc_GNBTEstimatedAmortizationExpenseTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTEstimatedAmortizationExpenseTableTextBlock_80" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:label="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_80" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SummaryOfAllocationOfPreliminaryPurchasePriceTableTextBlock" xlink:label="loc_GNBTSummaryOfAllocationOfPreliminaryPurchasePriceTableTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTSummaryOfAllocationOfPreliminaryPurchasePriceTableTextBlock_80" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock" xlink:label="loc_us-gaapScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock_80" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:label="loc_us-gaapBusinessAcquisitionProFormaInformationTextBlock_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessAcquisitionProFormaInformationTextBlock_80" xlink:type="arc" order="9" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/DerivativeLiabilityTables" xlink:title="00000034 - Disclosure - Derivative Liability (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/WarrantsTables" xlink:title="00000035 - Disclosure - Warrants (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Stock-basedCompensationTables" xlink:title="00000036 - Disclosure - Stock-Based Compensation (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/OrganizationOfBusinessAndGoingConcernDetailsNarrative" xlink:title="00000037 - Disclosure - Organization of Business and Going Concern (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_HemaDiagnosticSystemsMember" xlink:label="loc_GNBTHemaDiagnosticSystemsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_GNBTHemaDiagnosticSystemsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MajorityInterest" xlink:label="loc_GNBTMajorityInterest_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTMajorityInterest_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WorkingCapitalDeficiency" xlink:label="loc_GNBTWorkingCapitalDeficiency_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTWorkingCapitalDeficiency_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SecuredPromissoryNoteDescription" xlink:label="loc_GNBTSecuredPromissoryNoteDescription_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTSecuredPromissoryNoteDescription_50" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:title="00000038 - Disclosure - Summary of Significant Accounting Policies (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeAxis" xlink:label="loc_us-gaapOptionIndexedToIssuersEquityTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapOptionIndexedToIssuersEquityTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaapOptionIndexedToIssuersEquityTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapOptionIndexedToIssuersEquityTypeAxis" xlink:to="loc_us-gaapOptionIndexedToIssuersEquityTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaapOptionIndexedToIssuersEquityTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapOptionIndexedToIssuersEquityTypeAxis" xlink:to="loc_us-gaapOptionIndexedToIssuersEquityTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CallOptionMember" xlink:label="loc_us-gaapCallOptionMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapOptionIndexedToIssuersEquityTypeDomain" xlink:to="loc_us-gaapCallOptionMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaapFairValueInputsLevel1Member_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel1Member_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaapFairValueInputsLevel2Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel2Member_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaapFairValueInputsLevel3Member_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel3Member_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaapFairValueByLiabilityClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFairValueByLiabilityClassAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByLiabilityClassAxis" xlink:to="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByLiabilityClassAxis" xlink:to="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_DerivativeliabilityMember" xlink:label="loc_GNBTDerivativeliabilityMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_GNBTDerivativeliabilityMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WarrantsMember" xlink:label="loc_GNBTWarrantsMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_GNBTWarrantsMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CallOptions" xlink:label="loc_GNBTCallOptions_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCallOptions_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaapDerivativeLiabilitiesCurrent_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDerivativeLiabilitiesCurrent_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WarrantsToBeIssued" xlink:label="loc_GNBTWarrantsToBeIssued_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTWarrantsToBeIssued_130" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_Total" xlink:label="loc_GNBTTotal_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTTotal_130" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:title="00000039 - Disclosure - Summary of Significant Accounting Policies (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaapComputerEquipmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapComputerEquipmentMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaapMachineryAndEquipmentMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapMachineryAndEquipmentMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaapFurnitureAndFixturesMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapFurnitureAndFixturesMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapIndefiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapIndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapIndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapIndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_EmpireStatePharmacyMember" xlink:label="loc_GNBTEmpireStatePharmacyMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTEmpireStatePharmacyMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_GrainlandPharmacyAssetsMember" xlink:label="loc_GNBTGrainlandPharmacyAssetsMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTGrainlandPharmacyAssetsMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives" xlink:label="loc_us-gaapPropertyPlantAndEquipmentEstimatedUsefulLives_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentEstimatedUsefulLives_120" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesNoncurrent" xlink:label="loc_us-gaapLiabilitiesNoncurrent_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLiabilitiesNoncurrent_120" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaapAssetImpairmentCharges_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAssetImpairmentCharges_120" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InventoryWriteDown" xlink:label="loc_us-gaapInventoryWriteDown_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInventoryWriteDown_120" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredIncomeTaxes" xlink:label="loc_us-gaapIncreaseDecreaseInDeferredIncomeTaxes_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncreaseDecreaseInDeferredIncomeTaxes_120" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_120" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/LoanFromRelatedPartiesDetailsNarrative" xlink:title="00000040 - Disclosure - Loan from Related Parties (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BerkmanMember" xlink:label="loc_GNBTBerkmanMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTBerkmanMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_HemaDiagnosticSystemsMember" xlink:label="loc_GNBTHemaDiagnosticSystemsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTHemaDiagnosticSystemsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTRegentysMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PantheonMember" xlink:label="loc_GNBTPantheonMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTPantheonMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:label="loc_us-gaapLongtermDebtWeightedAverageInterestRate_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLongtermDebtWeightedAverageInterestRate_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtPercentageBearingFixedInterestAmount" xlink:label="loc_us-gaapLongtermDebtPercentageBearingFixedInterestAmount_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLongtermDebtPercentageBearingFixedInterestAmount_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:label="loc_us-gaapInterestPayableCurrent_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInterestPayableCurrent_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AgreementTerms" xlink:label="loc_GNBTAgreementTerms_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAgreementTerms_90" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DueToRelatedPartiesCurrent" xlink:label="loc_us-gaapDueToRelatedPartiesCurrent_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDueToRelatedPartiesCurrent_90" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfDebt" xlink:label="loc_us-gaapRepaymentsOfDebt_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRepaymentsOfDebt_90" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromLoans" xlink:label="loc_us-gaapProceedsFromLoans_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProceedsFromLoans_90" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaapAccountsReceivableNetCurrent_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsReceivableNetCurrent_90" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:title="00000041 - Disclosure - Commitments and Contingencies (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srtLitigationCaseAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtLitigationCaseAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srtLitigationCaseTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtLitigationCaseAxis" xlink:to="loc_srtLitigationCaseTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srtLitigationCaseTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtLitigationCaseAxis" xlink:to="loc_srtLitigationCaseTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_DamagesForUnpaidInvoicesMember" xlink:label="loc_GNBTDamagesForUnpaidInvoicesMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtLitigationCaseTypeDomain" xlink:to="loc_GNBTDamagesForUnpaidInvoicesMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BreachOfContractMember" xlink:label="loc_GNBTBreachOfContractMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtLitigationCaseTypeDomain" xlink:to="loc_GNBTBreachOfContractMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AlternativeExecutionGroupMember" xlink:label="loc_GNBTAlternativeExecutionGroupMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTAlternativeExecutionGroupMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ValueOfDamagesSought" xlink:label="loc_GNBTValueOfDamagesSought_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTValueOfDamagesSought_150" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainContingencyUnrecordedAmount" xlink:label="loc_us-gaapGainContingencyUnrecordedAmount_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGainContingencyUnrecordedAmount_150" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyLawsuitFilingDate" xlink:label="loc_us-gaapLossContingencyLawsuitFilingDate_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLossContingencyLawsuitFilingDate_150" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNameOfPlaintiff" xlink:label="loc_us-gaapLossContingencyNameOfPlaintiff_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLossContingencyNameOfPlaintiff_150" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainLossRelatedToLitigationSettlement" xlink:label="loc_us-gaapGainLossRelatedToLitigationSettlement_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGainLossRelatedToLitigationSettlement_150" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InterestPerAnnumFailureToPaySettlement" xlink:label="loc_GNBTInterestPerAnnumFailureToPaySettlement_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInterestPerAnnumFailureToPaySettlement_150" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LitigationSettlementInterest" xlink:label="loc_us-gaapLitigationSettlementInterest_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLitigationSettlementInterest_150" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCommitmentsDescription" xlink:label="loc_us-gaapOtherCommitmentsDescription_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherCommitmentsDescription_150" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaapOperatingLeasesFutureMinimumPaymentsDueInTwoYears_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLeasesFutureMinimumPaymentsDueInTwoYears_150" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaapOperatingLeasesFutureMinimumPaymentsDueInThreeYears_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLeasesFutureMinimumPaymentsDueInThreeYears_150" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty" xlink:label="loc_us-gaapLitigationSettlementAmountAwardedToOtherParty_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLitigationSettlementAmountAwardedToOtherParty_150" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LitigationAwardsExercisableShares" xlink:label="loc_GNBTLitigationAwardsExercisableShares_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLitigationAwardsExercisableShares_150" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ExercisePrice" xlink:label="loc_GNBTExercisePrice_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTExercisePrice_150" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MemorandumOfUnderstandingDescription" xlink:label="loc_GNBTMemorandumOfUnderstandingDescription_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTMemorandumOfUnderstandingDescription_150" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_150" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IndefinitelivedIntangibleAssetsAcquired" xlink:label="loc_us-gaapIndefinitelivedIntangibleAssetsAcquired_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIndefinitelivedIntangibleAssetsAcquired_150" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaapFairValueAdjustmentOfWarrants_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFairValueAdjustmentOfWarrants_150" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LiquidatedDamages" xlink:label="loc_GNBTLiquidatedDamages_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLiquidatedDamages_150" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AccruedLiquidatedDamages" xlink:label="loc_GNBTAccruedLiquidatedDamages_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAccruedLiquidatedDamages_150" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xlink:label="loc_us-gaapMalpracticeLossContingencyAccrualUndiscounted_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapMalpracticeLossContingencyAccrualUndiscounted_150" xlink:type="arc" order="19" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/LeasesDetails" xlink:title="00000042 - Disclosure - Leases (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/LeasesDetailsNarrative" xlink:title="00000043 - Disclosure - Leases (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/PropertyAndEquipmentDetails" xlink:title="00000044 - Disclosure - Property and Equipment (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ComputersAndTechnologicalAssetsMember" xlink:label="loc_GNBTComputersAndTechnologicalAssetsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_GNBTComputersAndTechnologicalAssetsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaapMachineryAndEquipmentMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapMachineryAndEquipmentMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaapFurnitureAndFixturesMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapFurnitureAndFixturesMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaapLeaseholdImprovementsMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapLeaseholdImprovementsMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaapPropertyPlantAndEquipmentGross_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentGross_160" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaapAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_160" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_160" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/PropertyAndEquipmentDetailsNarrative" xlink:title="00000045 - Disclosure - Property and Equipment (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoMember" xlink:label="loc_GNBTVenetoMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_GrainlandPharmaciesHoldingsMember" xlink:label="loc_GNBTGrainlandPharmaciesHoldingsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTGrainlandPharmaciesHoldingsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaapDepreciation_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDepreciation_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisposals" xlink:label="loc_us-gaapPropertyPlantAndEquipmentDisposals_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentDisposals_70" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ImpairmentOfLonglivedAssets" xlink:label="loc_GNBTImpairmentOfLonglivedAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTImpairmentOfLonglivedAssets_70" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/StockholdersEquityDetailsNarrative" xlink:title="00000046 - Disclosure - Stockholders&apos; Equity (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockPurchaseAgreementMember" xlink:label="loc_GNBTStockPurchaseAgreementMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_GNBTStockPurchaseAgreementMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRegentysMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PostReverseStockSplitMember" xlink:label="loc_GNBTPostReverseStockSplitMember_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPostReverseStockSplitMember_260" xlink:type="arc" order="261" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NetPurchasePriceMember" xlink:label="loc_GNBTNetPurchasePriceMember_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTNetPurchasePriceMember_270" xlink:type="arc" order="271" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AfterMember" xlink:label="loc_GNBTAfterMember_280" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAfterMember_280" xlink:type="arc" order="281" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AtClosingMember" xlink:label="loc_GNBTAtClosingMember_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAtClosingMember_290" xlink:type="arc" order="291" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MedisourceMember" xlink:label="loc_GNBTMedisourceMember_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTMedisourceMember_340" xlink:type="arc" order="341" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PantheonMember" xlink:label="loc_GNBTPantheonMember_350" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPantheonMember_350" xlink:type="arc" order="351" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NGDxMember" xlink:label="loc_GNBTNGDxMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTNGDxMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_HemaDiagnosticSystemsMember" xlink:label="loc_GNBTHemaDiagnosticSystemsMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTHemaDiagnosticSystemsMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BhSanfordMember" xlink:label="loc_GNBTBhSanfordMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTBhSanfordMember_160" xlink:type="arc" order="161" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SalvoMember" xlink:label="loc_GNBTSalvoMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTSalvoMember_170" xlink:type="arc" order="171" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MoscatoMember" xlink:label="loc_GNBTMoscatoMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTMoscatoMember_180" xlink:type="arc" order="181" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeriesHPreferredStockMember" xlink:label="loc_us-gaapSeriesHPreferredStockMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesHPreferredStockMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SeriesIPreferredStockMember" xlink:label="loc_GNBTSeriesIPreferredStockMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_GNBTSeriesIPreferredStockMember_120" xlink:type="arc" order="121" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenSeriesAPreferredStockMember" xlink:label="loc_GNBTOlaregenSeriesAPreferredStockMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_GNBTOlaregenSeriesAPreferredStockMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysSeriesARedeemableConvertiblePreferredStockMember" xlink:label="loc_GNBTRegentysSeriesARedeemableConvertiblePreferredStockMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_GNBTRegentysSeriesARedeemableConvertiblePreferredStockMember_140" xlink:type="arc" order="141" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConversionOfStockByUniqueDescriptionAxis" xlink:label="loc_us-gaapConversionOfStockByUniqueDescriptionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapConversionOfStockByUniqueDescriptionAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConversionOfStockNameDomain" xlink:label="loc_us-gaapConversionOfStockNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConversionOfStockByUniqueDescriptionAxis" xlink:to="loc_us-gaapConversionOfStockNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConversionOfStockNameDomain" xlink:label="loc_us-gaapConversionOfStockNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConversionOfStockByUniqueDescriptionAxis" xlink:to="loc_us-gaapConversionOfStockNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RemainToBeIssuedMember" xlink:label="loc_GNBTRemainToBeIssuedMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConversionOfStockNameDomain" xlink:to="loc_GNBTRemainToBeIssuedMember_200" xlink:type="arc" order="201" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesIssued_400" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AcquisitionInHds" xlink:label="loc_GNBTAcquisitionInHds_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAcquisitionInHds_400" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SharesOfCommonStockObligatedToIssue" xlink:label="loc_GNBTSharesOfCommonStockObligatedToIssue_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTSharesOfCommonStockObligatedToIssue_400" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPurchaseWarrantsExercisePrice" xlink:label="loc_GNBTCommonStockPurchaseWarrantsExercisePrice_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockPurchaseWarrantsExercisePrice_400" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:label="loc_us-gaapConvertiblePreferredStockSharesIssuedUponConversion_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapConvertiblePreferredStockSharesIssuedUponConversion_400" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConvertedStockAmountPaymentToHolder" xlink:label="loc_GNBTConvertedStockAmountPaymentToHolder_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConvertedStockAmountPaymentToHolder_400" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaapSharesIssued_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesIssued_400" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayableShares" xlink:label="loc_GNBTCommonStockPayableShares_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockPayableShares_400" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayableAmount" xlink:label="loc_GNBTCommonStockPayableAmount_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockPayableAmount_400" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WarrantsExercised" xlink:label="loc_GNBTWarrantsExercised_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTWarrantsExercised_400" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaapPreferredStockSharesAuthorized_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesAuthorized_400" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_400" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_400" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaapPreferredStockValue_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockValue_400" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="loc_us-gaapNetIncomeLossAttributableToNoncontrollingInterest_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLossAttributableToNoncontrollingInterest_400" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InvestmentInSubsidiaryByNoncontrollingInterest" xlink:label="loc_GNBTInvestmentInSubsidiaryByNoncontrollingInterest_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInvestmentInSubsidiaryByNoncontrollingInterest_400" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaapMinorityInterest_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapMinorityInterest_400" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LoiTerms" xlink:label="loc_GNBTLoiTerms_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLoiTerms_400" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_400" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NotesPayableForAcquisition" xlink:label="loc_GNBTNotesPayableForAcquisition_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNotesPayableForAcquisition_400" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfPreferredStock" xlink:label="loc_GNBTNumberOfPreferredStock_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfPreferredStock_400" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_400" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_400" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockIssuedForConversionOfNotePayableShares" xlink:label="loc_GNBTStockIssuedForConversionOfNotePayableShares_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTStockIssuedForConversionOfNotePayableShares_400" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockIssuedForConversionOfNotePayableValue" xlink:label="loc_GNBTStockIssuedForConversionOfNotePayableValue_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTStockIssuedForConversionOfNotePayableValue_400" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FairValue" xlink:label="loc_GNBTFairValue_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTFairValue_400" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionSharePrice" xlink:label="loc_us-gaapBusinessAcquisitionSharePrice_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessAcquisitionSharePrice_400" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CancellationOfCommonStock" xlink:label="loc_GNBTCancellationOfCommonStock_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCancellationOfCommonStock_400" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaapCommonStockSharesOutstanding_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesOutstanding_400" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaapPreferredStockSharesOutstanding_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesOutstanding_400" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoncontrollingInterest" xlink:label="loc_GNBTNoncontrollingInterest_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoncontrollingInterest_400" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PercentageOfNoncontrollingInterest" xlink:label="loc_GNBTPercentageOfNoncontrollingInterest_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPercentageOfNoncontrollingInterest_400" xlink:type="arc" order="31" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/RedeemableNon-controllingInterestDetailsNarrative" xlink:title="00000047 - Disclosure - Redeemable Non-Controlling Interest (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/InventoryDetails" xlink:title="00000048 - Disclosure - Inventory (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NotesPayableDetailsNarrative" xlink:title="00000049 - Disclosure - Notes Payable (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaapFinancialInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFinancialInstrumentAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PrincipalMember" xlink:label="loc_GNBTPrincipalMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_GNBTPrincipalMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AccruedInterestMember" xlink:label="loc_GNBTAccruedInterestMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_GNBTAccruedInterestMember_90" xlink:type="arc" order="92" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRegentysMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaapLongtermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapLongtermDebtTypeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaapLongtermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapLongtermDebtTypeAxis" xlink:to="loc_us-gaapLongtermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaapLongtermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLongtermDebtTypeAxis" xlink:to="loc_us-gaapLongtermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NotePayableMember" xlink:label="loc_GNBTNotePayableMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLongtermDebtTypeDomain" xlink:to="loc_GNBTNotePayableMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_280" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_280" xlink:type="arc" order="281" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_290" xlink:type="arc" order="291" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_370" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PurchasePriceOfNote" xlink:label="loc_GNBTPurchasePriceOfNote_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPurchasePriceOfNote_370" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InvestorFee" xlink:label="loc_GNBTInvestorFee_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInvestorFee_370" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesReceivableRelatedParties" xlink:label="loc_us-gaapNotesReceivableRelatedParties_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNotesReceivableRelatedParties_370" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_370" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_370" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_370" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockIssuedInSatisfactionNotes" xlink:label="loc_GNBTCommonStockIssuedInSatisfactionNotes_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockIssuedInSatisfactionNotes_370" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfWarrantsSold" xlink:label="loc_GNBTNumberOfWarrantsSold_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfWarrantsSold_370" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PaymentOfPromissoryNote" xlink:label="loc_GNBTPaymentOfPromissoryNote_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPaymentOfPromissoryNote_370" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:label="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_370" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_370" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_370" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockPayable" xlink:label="loc_GNBTCommonStockPayable_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockPayable_370" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:label="loc_us-gaapDerivativeFairValueOfDerivativeLiability_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDerivativeFairValueOfDerivativeLiability_370" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts_370" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscount_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscount_370" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfCommonStockConverted" xlink:label="loc_GNBTNumberOfCommonStockConverted_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfCommonStockConverted_370" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaapDeferredTaxLiabilities_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDeferredTaxLiabilities_370" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayableCurrent" xlink:label="loc_us-gaapNotesPayableCurrent_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNotesPayableCurrent_370" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_370" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainsLossesOnRestructuringOfDebt" xlink:label="loc_us-gaapGainsLossesOnRestructuringOfDebt_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGainsLossesOnRestructuringOfDebt_370" xlink:type="arc" order="21" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/IncomeTaxes-DeferredIncomeTaxesDetails" xlink:title="00000050 - Disclosure - Income Taxes - Deferred income taxes (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/IncomeTaxes-ReconciliationOfEffectiveTaxRateDetails" xlink:title="00000051 - Disclosure - Income Taxes - Reconciliation of effective tax rate (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/IncomeTaxesDetailsNarrative" xlink:title="00000052 - Disclosure - Income Taxes (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_GenerexPharmaceuticalsMember" xlink:label="loc_GNBTGenerexPharmaceuticalsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTGenerexPharmaceuticalsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AntigenExpressMember" xlink:label="loc_GNBTAntigenExpressMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTAntigenExpressMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTRegentysMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTOlaregenMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PretaxGainOrLossArisingFromDomesticOperations" xlink:label="loc_GNBTPretaxGainOrLossArisingFromDomesticOperations_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPretaxGainOrLossArisingFromDomesticOperations_140" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PretaxLossesArisingFromForeignOperations" xlink:label="loc_GNBTPretaxLossesArisingFromForeignOperations_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPretaxLossesArisingFromForeignOperations_140" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaapOperatingLossCarryforwards_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLossCarryforwards_140" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredIncomeTaxes" xlink:label="loc_us-gaapIncreaseDecreaseInDeferredIncomeTaxes_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncreaseDecreaseInDeferredIncomeTaxes_140" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NetLossIncomePerShareEps-ComputationOfDilutedEpsDetails" xlink:title="00000053 - Disclosure - Net (Loss) / Income Per Share (&#8220;EPS&#8221;) - Computation of diluted EPS (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/NetIncomePerShareEps-ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareDetails" xlink:title="00000054 - Disclosure - Net Income Per Share (&#8220;EPS&#8221;) - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SeriesHConvertiblePreferredStockMember" xlink:label="loc_GNBTSeriesHConvertiblePreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_GNBTSeriesHConvertiblePreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SeriesIConvertiblePreferredStockMember" xlink:label="loc_GNBTSeriesIConvertiblePreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_GNBTSeriesIConvertiblePreferredStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConvertibleDebtsMember" xlink:label="loc_GNBTConvertibleDebtsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_GNBTConvertibleDebtsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockOptionsMember" xlink:label="loc_GNBTStockOptionsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_GNBTStockOptionsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_WarrantsMember" xlink:label="loc_GNBTWarrantsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_GNBTWarrantsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_190" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssetsIntangibleAssetsDetails" xlink:title="00000055 - Disclosure - Goodwill and Intangible Assets: Intangible assets (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InProcessResearchAndDevelopmentMember" xlink:label="loc_us-gaapInProcessResearchAndDevelopmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapInProcessResearchAndDevelopmentMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaapNoncompeteAgreementsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapNoncompeteAgreementsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaapSoftwareDevelopmentMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapSoftwareDevelopmentMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VendorAgreementsAndOtherIntangibleMember" xlink:label="loc_GNBTVendorAgreementsAndOtherIntangibleMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTVendorAgreementsAndOtherIntangibleMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaapOtherIntangibleAssetsMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapOtherIntangibleAssetsMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsGross_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsGross_170" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_170" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsNet_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsNet_170" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssetsEstimatedAmortizationExpenseDetails" xlink:title="00000056 - Disclosure - Goodwill and Intangible Assets: Estimated amortization expense (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssetsChangesInValueOfGoodwillDetails" xlink:title="00000057 - Disclosure - Goodwill and Intangible Assets: Changes in value of goodwill (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillMember" xlink:label="loc_us-gaapGoodwillMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapGoodwillMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoMember" xlink:label="loc_GNBTVenetoMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRegentysMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGoodwill_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:label="loc_us-gaapFinitelivedIntangibleAssetsAcquired1_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFinitelivedIntangibleAssetsAcquired1_50" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/GoodwillAndIntangibleAssetsDetailsNarrative" xlink:title="00000058 - Disclosure - Goodwill and Intangible Assets (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-NetPurchasePriceOfNgdxDetails" xlink:title="00000059 - Disclosure - Acquisitions - Net purchase price of NGDx (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AtClosingMember" xlink:label="loc_GNBTAtClosingMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAtClosingMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AfterMember" xlink:label="loc_GNBTAfterMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAfterMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PostReverseStockSplitMember" xlink:label="loc_GNBTPostReverseStockSplitMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPostReverseStockSplitMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NetPurchasePriceMember" xlink:label="loc_GNBTNetPurchasePriceMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTNetPurchasePriceMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PurchasePriceAbstract" xlink:label="loc_GNBTPurchasePriceAbstract_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPurchasePriceAbstract_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockPriceAtClosing" xlink:label="loc_GNBTStockPriceAtClosing_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_GNBTPurchasePriceAbstract_90" xlink:to="loc_GNBTStockPriceAtClosing_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_GNBTPurchasePriceAbstract_90" xlink:to="loc_us-gaapCommonStockSharesIssued_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1" xlink:label="loc_us-gaapBusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_GNBTPurchasePriceAbstract_90" xlink:to="loc_us-gaapBusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_90" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-FairValueAssumptionsUsedInAccountingForWarrantsDetails" xlink:title="00000060 - Disclosure - Acquisitions - Fair Value Assumptions Used in Accounting for Warrants (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_us-gaapWarrantMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_50" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_50" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharePrice_50" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-FairValueAssumptionsUsedInAccountingForCallOptionsDetails" xlink:title="00000061 - Disclosure - Acquisitions - Fair Value Assumptions Used in Accounting for Call Options (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CallOptionMember" xlink:label="loc_us-gaapCallOptionMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_us-gaapCallOptionMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharePrice_50" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-PurchasePriceAllocatedAsOfAcquisitionDateDetails" xlink:title="00000062 - Disclosure - Acquisitions - Purchase price allocated as of acquisition date (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AllocationAdjustmentsMember" xlink:label="loc_GNBTAllocationAdjustmentsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAllocationAdjustmentsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FinalAllocationMember" xlink:label="loc_GNBTFinalAllocationMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTFinalAllocationMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PropertyAndEquipmentAcquisition" xlink:label="loc_GNBTPropertyAndEquipmentAcquisition_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPropertyAndEquipmentAcquisition_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ComputerSoftwareAcquisition" xlink:label="loc_GNBTComputerSoftwareAcquisition_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTComputerSoftwareAcquisition_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LeaseholdImprovementsAcquisition" xlink:label="loc_GNBTLeaseholdImprovementsAcquisition_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLeaseholdImprovementsAcquisition_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationAssetsAndLiabilitiesArisingFromContingenciesAmountRecognized" xlink:label="loc_us-gaapBusinessCombinationAssetsAndLiabilitiesArisingFromContingenciesAmountRecognized_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationAssetsAndLiabilitiesArisingFromContingenciesAmountRecognized_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract" xlink:label="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_40" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_40" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_40" xlink:to="loc_us-gaapGoodwill_40" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-SummaryOfAcquisitionDetails" xlink:title="00000063 - Disclosure - Acquisitions - Summary of Acquisition (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoFirstClosingMember" xlink:label="loc_GNBTVenetoFirstClosingMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoFirstClosingMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoSecondClosingMember" xlink:label="loc_GNBTVenetoSecondClosingMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoSecondClosingMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_TotalMember" xlink:label="loc_GNBTTotalMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTTotalMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_Total1Member" xlink:label="loc_GNBTTotal1Member_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTTotal1Member_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNet" xlink:label="loc_us-gaapAccountsReceivableNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsReceivableNet_70" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInventoryNet_70" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPrepaidExpenseCurrent_70" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_70" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherReceivables" xlink:label="loc_us-gaapOtherReceivables_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherReceivables_70" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesReceivableNet" xlink:label="loc_us-gaapNotesReceivableNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNotesReceivableNet_70" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssets" xlink:label="loc_us-gaapOtherAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherAssets_70" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_70" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_70" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLiabilitiesCurrent_70" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNotesPayable_70" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_70" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_70" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGoodwill_70" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_70" xlink:type="arc" order="15" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-FairValueOfMedisourceAcquisitionDetails" xlink:title="00000064 - Disclosure - Acquisitions - Fair Value of the Medisource Acquisition (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MedisourceMember" xlink:label="loc_GNBTMedisourceMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTMedisourceMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherAssetsCurrent_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_20" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_20" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NetTangibleAssets" xlink:label="loc_GNBTNetTangibleAssets_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNetTangibleAssets_20" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_TradenameTrademarks" xlink:label="loc_GNBTTradenameTrademarks_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTTradenameTrademarks_20" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BusinessContracts" xlink:label="loc_GNBTBusinessContracts_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTBusinessContracts_20" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_Noncompetes" xlink:label="loc_GNBTNoncompetes_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoncompetes_20" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract" xlink:label="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FairValueOfCommonStock" xlink:label="loc_GNBTFairValueOfCommonStock_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTFairValueOfCommonStock_20" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ContingentConsideration" xlink:label="loc_GNBTContingentConsideration_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTContingentConsideration_20" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConsiderationIncludedInConsultingAgreement" xlink:label="loc_GNBTConsiderationIncludedInConsultingAgreement_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTConsiderationIncludedInConsultingAgreement_20" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_20" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_us-gaapGoodwill_20" xlink:type="arc" order="14" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-FairValueOfPantheonAcquisitionDetails" xlink:title="00000065 - Disclosure - Acquisitions - Fair Value of the Pantheon Acquisition (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PantheonMember" xlink:label="loc_GNBTPantheonMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPantheonMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaapAccountsReceivableNetCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsReceivableNetCurrent_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPrepaidExpenseCurrent_20" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInventoryNet_20" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_20" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaapAccountsPayableCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsPayableCurrent_20" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccruedLiabilitiesCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccruedLiabilitiesCurrent_20" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NetTangibleAssets" xlink:label="loc_GNBTNetTangibleAssets_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNetTangibleAssets_20" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_TradenameTrademarks" xlink:label="loc_GNBTTradenameTrademarks_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTTradenameTrademarks_20" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_IpTechnology" xlink:label="loc_GNBTIpTechnology_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTIpTechnology_20" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoncompeteAgreement" xlink:label="loc_GNBTNoncompeteAgreement_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoncompeteAgreement_20" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CustomerBase" xlink:label="loc_GNBTCustomerBase_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCustomerBase_20" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract" xlink:label="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FairValueOfCommonStock" xlink:label="loc_GNBTFairValueOfCommonStock_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTFairValueOfCommonStock_20" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ContingentConsideration" xlink:label="loc_GNBTContingentConsideration_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTContingentConsideration_20" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConsiderationIncludedInConsultingAgreement" xlink:label="loc_GNBTConsiderationIncludedInConsultingAgreement_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_GNBTConsiderationIncludedInConsultingAgreement_20" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessCombinationConsiderationTransferredAbstract_20" xlink:to="loc_us-gaapGoodwill_20" xlink:type="arc" order="17" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-EstimatedAmortizationExpenseDetails" xlink:title="00000066 - Disclosure - Acquisitions - Estimated amortization expense (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PreliminaryFairValueMember" xlink:label="loc_GNBTPreliminaryFairValueMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPreliminaryFairValueMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaapSoftwareDevelopmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapSoftwareDevelopmentMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ReferralBaseMember" xlink:label="loc_GNBTReferralBaseMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTReferralBaseMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaapNoncompeteAgreementsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapNoncompeteAgreementsMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_TradenameTrademarksMember" xlink:label="loc_GNBTTradenameTrademarksMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTTradenameTrademarksMember_140" xlink:type="arc" order="142" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_IpTechnologyMember" xlink:label="loc_GNBTIpTechnologyMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTIpTechnologyMember_150" xlink:type="arc" order="152" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BusinessContractsMember" xlink:label="loc_GNBTBusinessContractsMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTBusinessContractsMember_160" xlink:type="arc" order="162" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CustomerBaseMember" xlink:label="loc_GNBTCustomerBaseMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_GNBTCustomerBaseMember_170" xlink:type="arc" order="172" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_260" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_260" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-PurchasePriceAsOfRegentysAcquisitionDetails" xlink:title="00000067 - Disclosure - Acquisitions - Purchase price as of the Regentys acquisition (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AllocationAdjustmentsMember" xlink:label="loc_GNBTAllocationAdjustmentsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAllocationAdjustmentsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RevisedAllocationMember" xlink:label="loc_GNBTRevisedAllocationMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRevisedAllocationMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherAssetsCurrent_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNotesPayable_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DueFromRelatedPartiesCurrent" xlink:label="loc_us-gaapDueFromRelatedPartiesCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDueFromRelatedPartiesCurrent_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaapDeferredTaxLiabilities_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDeferredTaxLiabilities_40" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InprocessResearchDevelopment" xlink:label="loc_GNBTInprocessResearchDevelopment_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInprocessResearchDevelopment_40" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoteReceivableFromGenerexs" xlink:label="loc_GNBTNoteReceivableFromGenerexs_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoteReceivableFromGenerexs_40" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="loc_us-gaapRedeemableNoncontrollingInterestEquityCarryingAmount_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRedeemableNoncontrollingInterestEquityCarryingAmount_40" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaapMinorityInterest_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapMinorityInterest_40" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CashPaidPriorToTimeOfClosings" xlink:label="loc_GNBTCashPaidPriorToTimeOfClosings_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCashPaidPriorToTimeOfClosings_40" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_40" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CashPaidPriorToTimeOfClosing" xlink:label="loc_GNBTCashPaidPriorToTimeOfClosing_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCashPaidPriorToTimeOfClosing_40" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoteReceivableFromGenerex" xlink:label="loc_GNBTNoteReceivableFromGenerex_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoteReceivableFromGenerex_40" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGoodwill_40" xlink:type="arc" order="15" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-PurchasePriceAsOfOlaregenAcquisitionDetails" xlink:title="00000068 - Disclosure - Acquisitions - Purchase price as of the Olaregen acquisition (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PreliminaryAllocationsMember" xlink:label="loc_GNBTPreliminaryAllocationsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPreliminaryAllocationsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AllocationAdjustmentsMember" xlink:label="loc_GNBTAllocationAdjustmentsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAllocationAdjustmentsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RevisedAllocationMember" xlink:label="loc_GNBTRevisedAllocationMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRevisedAllocationMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPrepaidExpenseCurrent_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInventoryNet_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherAssetsCurrent_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaapAccountsPayableCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccountsPayableCurrent_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccruedLiabilitiesCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAccruedLiabilitiesCurrent_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaapDeferredTaxLiabilities_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDeferredTaxLiabilities_40" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InprocessResearchDevelopment" xlink:label="loc_GNBTInprocessResearchDevelopment_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTInprocessResearchDevelopment_40" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoncompeteAgreement" xlink:label="loc_GNBTNoncompeteAgreement_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoncompeteAgreement_40" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoteReceivableFromGenerexs" xlink:label="loc_GNBTNoteReceivableFromGenerexs_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoteReceivableFromGenerexs_40" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaapMinorityInterest_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapMinorityInterest_40" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CashPaidPriorToTimeOfClosings" xlink:label="loc_GNBTCashPaidPriorToTimeOfClosings_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCashPaidPriorToTimeOfClosings_40" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_40" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CashPaidPriorToTimeOfClosing" xlink:label="loc_GNBTCashPaidPriorToTimeOfClosing_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCashPaidPriorToTimeOfClosing_40" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoteReceivableFromGenerex" xlink:label="loc_GNBTNoteReceivableFromGenerex_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoteReceivableFromGenerex_40" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGoodwill_40" xlink:type="arc" order="15" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-IntangibleAssetsDetails" xlink:title="00000069 - Disclosure - Acquisitions - Intangible assets (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaapSoftwareDevelopmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapSoftwareDevelopmentMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaapNoncompeteAgreementsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapNoncompeteAgreementsMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_50" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Acquisitions-UnauditedSupplementalProFormaDataDetails" xlink:title="00000070 - Disclosure - Acquisitions - Unaudited Supplemental Pro Forma Data (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/AcquisitionsDetailsNarrative" xlink:title="00000071 - Disclosure - Acquisitions (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_VenetoMember" xlink:label="loc_GNBTVenetoMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTVenetoMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTOlaregenMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTRegentysMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NetPurchasePriceMember" xlink:label="loc_GNBTNetPurchasePriceMember_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTNetPurchasePriceMember_190" xlink:type="arc" order="191" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PostReverseStockSplitMember" xlink:label="loc_GNBTPostReverseStockSplitMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPostReverseStockSplitMember_200" xlink:type="arc" order="201" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AfterMember" xlink:label="loc_GNBTAfterMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAfterMember_210" xlink:type="arc" order="211" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AtClosingMember" xlink:label="loc_GNBTAtClosingMember_220" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTAtClosingMember_220" xlink:type="arc" order="221" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_GrainlandPharmacyHoldingsMember" xlink:label="loc_GNBTGrainlandPharmacyHoldingsMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_GNBTGrainlandPharmacyHoldingsMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_EmpireStatePharmacyHoldingsMember" xlink:label="loc_GNBTEmpireStatePharmacyHoldingsMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_GNBTEmpireStatePharmacyHoldingsMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_BerkmanMember" xlink:label="loc_GNBTBerkmanMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTBerkmanMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionInterestAcquired1" xlink:label="loc_us-gaapNoncashOrPartNoncashAcquisitionInterestAcquired1_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNoncashOrPartNoncashAcquisitionInterestAcquired1_260" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AcquisitionOfOutstandingLimitedLiabilityCompanyUnits" xlink:label="loc_GNBTAcquisitionOfOutstandingLimitedLiabilityCompanyUnits_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAcquisitionOfOutstandingLimitedLiabilityCompanyUnits_260" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ValueOfSharesExchangedForOutstandingLimitedLiabilityUnits" xlink:label="loc_GNBTValueOfSharesExchangedForOutstandingLimitedLiabilityUnits_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTValueOfSharesExchangedForOutstandingLimitedLiabilityUnits_260" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesIssued_260" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonUnitIssued" xlink:label="loc_us-gaapCommonUnitIssued_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonUnitIssued_260" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CallOption" xlink:label="loc_GNBTCallOption_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCallOption_260" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CallOptions" xlink:label="loc_GNBTCallOptions_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCallOptions_260" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ChangesInFairValueOfContingentPurchaseConsiderations" xlink:label="loc_GNBTChangesInFairValueOfContingentPurchaseConsiderations_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTChangesInFairValueOfContingentPurchaseConsiderations_260" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TemporaryEquitySharesIssued" xlink:label="loc_us-gaapTemporaryEquitySharesIssued_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquitySharesIssued_260" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_260" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaapBusinessCombinationConsiderationTransferred1_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationConsiderationTransferred1_260" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationAsset" xlink:label="loc_us-gaapBusinessCombinationContingentConsiderationAsset_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessCombinationContingentConsiderationAsset_260" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AggregatePurchasePrice" xlink:label="loc_GNBTAggregatePurchasePrice_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTAggregatePurchasePrice_260" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SharesExercisable" xlink:label="loc_GNBTSharesExercisable_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTSharesExercisable_260" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_us-gaapDebtInstrumentFairValue_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentFairValue_260" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_260" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_260" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaapGoodwillImpairmentLoss_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGoodwillImpairmentLoss_260" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableDescription" xlink:label="loc_us-gaapBusinessAcquisitionEquityInterestIssuedOrIssuableDescription_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapBusinessAcquisitionEquityInterestIssuedOrIssuableDescription_260" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LoiDescription" xlink:label="loc_GNBTLoiDescription_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLoiDescription_260" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PaymentOfPromissoryNote" xlink:label="loc_GNBTPaymentOfPromissoryNote_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPaymentOfPromissoryNote_260" xlink:type="arc" order="20" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/DerivativeLiabilityDetails" xlink:title="00000072 - Disclosure - Derivative Liability (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaapFairValueByLiabilityClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFairValueByLiabilityClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByLiabilityClassAxis" xlink:to="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByLiabilityClassAxis" xlink:to="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_DerivativeLiabilityConvertibleNotesMember" xlink:label="loc_GNBTDerivativeLiabilityConvertibleNotesMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_GNBTDerivativeLiabilityConvertibleNotesMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_DerivativeLiabilityWarrantsMember" xlink:label="loc_GNBTDerivativeLiabilityWarrantsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_GNBTDerivativeLiabilityWarrantsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_DerivativeLiabilityDownsideProtectionMember" xlink:label="loc_GNBTDerivativeLiabilityDownsideProtectionMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_GNBTDerivativeLiabilityDownsideProtectionMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaapDerivativeLiabilities_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDerivativeLiabilities_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInDerivativeLiabilities" xlink:label="loc_us-gaapIncreaseDecreaseInDerivativeLiabilities_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncreaseDecreaseInDerivativeLiabilities_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:label="loc_us-gaapDerivativeGainLossOnDerivativeNet_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDerivativeGainLossOnDerivativeNet_130" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ChangeDueToExerciseRedemptions" xlink:label="loc_GNBTChangeDueToExerciseRedemptions_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTChangeDueToExerciseRedemptions_130" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/WarrantsDetails" xlink:title="00000073 - Disclosure - Warrants (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/WarrantsDetailsNarrative" xlink:title="00000074 - Disclosure - Warrants (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InvestorsMember" xlink:label="loc_GNBTInvestorsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTInvestorsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AEXGMember" xlink:label="loc_GNBTAEXGMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTAEXGMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FormershareholderMember" xlink:label="loc_GNBTFormershareholderMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTFormershareholderMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfWarrantsIssued" xlink:label="loc_GNBTNumberOfWarrantsIssued_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfWarrantsIssued_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations_70" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Stock-basedCompensation-CommonStockOptionsGrantedForfeitedOrExpiredAndExercisedDetails" xlink:title="00000075 - Disclosure - Stock-Based Compensation - Common stock options granted, forfeited or expired and exercised (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Stock-basedCompensation-FairValueAssumptionsUsedInBlack-scholesOption-pricingDetails" xlink:title="00000076 - Disclosure - Stock-Based Compensation - Fair value assumptions used in Black-Scholes option-pricing (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_110" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_110" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_110" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_110" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_110" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharePrice_110" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/Stock-basedCompensationDetailsNarrative" xlink:title="00000077 - Disclosure - Stock-Based Compensation (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockOptionPlan2006Member" xlink:label="loc_GNBTStockOptionPlan2006Member_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_GNBTStockOptionPlan2006Member_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockOptionPlan2017Member" xlink:label="loc_GNBTStockOptionPlan2017Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_GNBTStockOptionPlan2017Member_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockOptionPlan2019Member" xlink:label="loc_GNBTStockOptionPlan2019Member_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_GNBTStockOptionPlan2019Member_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockOptionMember" xlink:label="loc_us-gaapStockOptionMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapStockOptionMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaapCommonStockCapitalSharesReservedForFutureIssuance_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockCapitalSharesReservedForFutureIssuance_180" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingPeriodIncreaseDecrease" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingPeriodIncreaseDecrease_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingPeriodIncreaseDecrease_180" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MarketValue" xlink:label="loc_GNBTMarketValue_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTMarketValue_180" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_180" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensation_180" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_180" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_180" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://generex.com/role/SubsequentEventsDetailsNarrative" xlink:title="00000078 - Disclosure - Subsequent Events (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaapFinancialInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapFinancialInstrumentAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PrincipalMember" xlink:label="loc_GNBTPrincipalMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_GNBTPrincipalMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InterestMember" xlink:label="loc_GNBTInterestMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_GNBTInterestMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_AccruedInterestMember" xlink:label="loc_GNBTAccruedInterestMember_470" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_GNBTAccruedInterestMember_470" xlink:type="arc" order="472" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PantheonMember" xlink:label="loc_GNBTPantheonMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTPantheonMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_MediSourcePartnersMember" xlink:label="loc_GNBTMediSourcePartnersMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_GNBTMediSourcePartnersMember_80" xlink:type="arc" order="82" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PublicSecuredFinancingFacilityAgreementMember" xlink:label="loc_GNBTPublicSecuredFinancingFacilityAgreementMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_GNBTPublicSecuredFinancingFacilityAgreementMember_100" xlink:type="arc" order="102" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_SecuritiesPurchaseAgreementMember" xlink:label="loc_GNBTSecuritiesPurchaseAgreementMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_GNBTSecuritiesPurchaseAgreementMember_110" xlink:type="arc" order="112" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ShareExchangeAgreementMember" xlink:label="loc_GNBTShareExchangeAgreementMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_GNBTShareExchangeAgreementMember_140" xlink:type="arc" order="142" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_EquityPurchaseAgreementMember" xlink:label="loc_GNBTEquityPurchaseAgreementMember_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_GNBTEquityPurchaseAgreementMember_340" xlink:type="arc" order="342" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_InvestorsMember" xlink:label="loc_GNBTInvestorsMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTInvestorsMember_100" xlink:type="arc" order="103" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_OlaregenMember" xlink:label="loc_GNBTOlaregenMember_500" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTOlaregenMember_500" xlink:type="arc" order="502" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_RegentysMember" xlink:label="loc_GNBTRegentysMember_510" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_GNBTRegentysMember_510" xlink:type="arc" order="512" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ALTuCELLMember" xlink:label="loc_GNBTALTuCELLMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_GNBTALTuCELLMember_200" xlink:type="arc" order="202" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_770" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_770" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_770" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaapRepaymentsOfLongTermDebt_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRepaymentsOfLongTermDebt_770" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FinancialAdvisoryServicesDescription" xlink:label="loc_GNBTFinancialAdvisoryServicesDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTFinancialAdvisoryServicesDescription_770" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_FinancingFacilityDescription" xlink:label="loc_GNBTFinancingFacilityDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTFinancingFacilityDescription_770" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_770" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_770" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_770" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfWarrantsSold" xlink:label="loc_GNBTNumberOfWarrantsSold_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfWarrantsSold_770" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NoteDescription" xlink:label="loc_GNBTNoteDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNoteDescription_770" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfSharesIncreased" xlink:label="loc_GNBTNumberOfSharesIncreased_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfSharesIncreased_770" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_LetterOfIntentDescription" xlink:label="loc_GNBTLetterOfIntentDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTLetterOfIntentDescription_770" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_NumberOfSharesCancelled" xlink:label="loc_GNBTNumberOfSharesCancelled_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTNumberOfSharesCancelled_770" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_ConsultingServicesDescription" xlink:label="loc_GNBTConsultingServicesDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTConsultingServicesDescription_770" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_PerformanceIncentiveDecription" xlink:label="loc_GNBTPerformanceIncentiveDecription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTPerformanceIncentiveDecription_770" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:label="loc_us-gaapConvertiblePreferredStockSharesIssuedUponConversion_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapConvertiblePreferredStockSharesIssuedUponConversion_770" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_CommonStockDescription" xlink:label="loc_GNBTCommonStockDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTCommonStockDescription_770" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="gnbt-20191031.xsd#GNBT_StockPurchaseAgreementDescription" xlink:label="loc_GNBTStockPurchaseAgreementDescription_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_GNBTStockPurchaseAgreementDescription_770" xlink:type="arc" order="18" />
    </link:definitionLink>
</link:linkbase>


