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  <xsd:element abstract="true" id="regn_DerivativeInstrumentsandHedgingActivitiesAbstract" name="DerivativeInstrumentsandHedgingActivitiesAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_DistributionRelatedFeesMember" name="DistributionRelatedFeesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_EYLEAMember" name="EYLEAMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EstimatedUsefulLivesOfPropertyPlantAndEquipmentTableTextBlock" name="EstimatedUsefulLivesOfPropertyPlantAndEquipmentTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ExcessShareOfProfitNotRequiredToToBeAppliedToReimburseDevelopmentCost" name="ExcessShareOfProfitNotRequiredToToBeAppliedToReimburseDevelopmentCost" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ExecutiveStockPurchasePlanAbstract" name="ExecutiveStockPurchasePlanAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ExercisePriceEqualToMarketPriceAbstract" name="ExercisePriceEqualToMarketPriceAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_EyleaNetProductSalesMember" name="EyleaNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_FacilityLeaseObligationsAbstract" name="FacilityLeaseObligationsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_FacilityLeaseObligationsAxis" name="FacilityLeaseObligationsAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_FacilityLeaseObligationsNameDomain" name="FacilityLeaseObligationsNameDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_FacilityLeasesFutureMinimumPaymentsDueAbstract" name="FacilityLeasesFutureMinimumPaymentsDueAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_FacilityPurchasePrice" name="FacilityPurchasePrice" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_February2016AgreementMember" name="February2016AgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_FundingMaximumofResearchActivitiesPerAgreement" name="FundingMaximumofResearchActivitiesPerAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_FutureDevelopmentMilestonePaymentCompanyisEligibletoReceive" name="FutureDevelopmentMilestonePaymentCompanyisEligibletoReceive" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Futurepaymenttobemadeundertermsofamendedlicensingagreement" name="Futurepaymenttobemadeundertermsofamendedlicensingagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_GrosssalesrevenueMember" name="GrosssalesrevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_IOAgreementMember" name="IOAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_IODiscoveryAgreementMember" name="IODiscoveryAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_IOLicenseandCollaborationAgreementMember" name="IOLicenseandCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ImmunooncologyAgreementMember" name="ImmunooncologyAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Increaseamountofshareddevelopmentcosts" name="Increaseamountofshareddevelopmentcosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_IncrementalCommonSharesAttributableToNonvestedRestrictedShares" name="IncrementalCommonSharesAttributableToNonvestedRestrictedShares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Initialtermoflease" name="Initialtermoflease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_IntellaTherapeuticsMember" name="IntellaTherapeuticsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Interestexpenseinconnectionwithcapitalandfacilityleases" name="Interestexpenseinconnectionwithcapitalandfacilityleases" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthssalesatwhichsalesmilestonepaymentswerereceived200million" name="Levelsoftwelvemonthssalesatwhichsalesmilestonepaymentswerereceived200million" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LicenseAgreementWithAstellasPharmaIncMember" name="LicenseAgreementWithAstellasPharmaIncMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Licenseagreementterm" name="Licenseagreementterm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LongTermIncentivePlan2000Member" name="LongTermIncentivePlan2000Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LongTermIncentivePlan2014Member" name="LongTermIncentivePlan2014Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_LossContingencyDamagesSoughtperunitproduced." name="LossContingencyDamagesSoughtperunitproduced." nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" name="MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" name="MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_Maximumadvancenoticerequiredtoterminatecollaborationagreement" name="Maximumadvancenoticerequiredtoterminatecollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="us-types:durationStringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Maximumamountofshareddevelopmentcosts" name="Maximumamountofshareddevelopmentcosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_Maximumamountofwarrantpayable" name="Maximumamountofwarrantpayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Maximumsharesthecollaboratorcouldsell" name="Maximumsharesthecollaboratorcouldsell" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_McKessonCorporationMember" name="McKessonCorporationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Minimumadvancenoticerequiredtoterminatecollaborationagreement" name="Minimumadvancenoticerequiredtoterminatecollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_MitsubishiTanabePharmaCorporationMTPCMember" name="MitsubishiTanabePharmaCorporationMTPCMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NetCarryingAmountOfLiabilityComponentAbstract" name="NetCarryingAmountOfLiabilityComponentAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NetproductsalesTableTextBlock" name="NetproductsalesTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Netprofitlossfromcommercializationofproductsundercollaborationagreement" name="Netprofitlossfromcommercializationofproductsundercollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NonPerformanceBasedStockOptionsMember" name="NonPerformanceBasedStockOptionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_November2016AgreementMemberMember" name="November2016AgreementMemberMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberOfDaysOfAdvanceWrittenNoticeToTerminateAgreement" name="NumberOfDaysOfAdvanceWrittenNoticeToTerminateAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberofdemandrightstorequiretheCompanytoconductregisteredunderwrittenpublicoffering" name="NumberofdemandrightstorequiretheCompanytoconductregisteredunderwrittenpublicoffering" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Numberofnewlyissuedsharespurchased" name="Numberofnewlyissuedsharespurchased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_OtherCollaborationRevenue" name="OtherCollaborationRevenue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherDeferredRevenueAgreementsMember" name="OtherDeferredRevenueAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherSalesRelatedDeductionsMember" name="OtherSalesRelatedDeductionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Outofperiodadjustment" name="Outofperiodadjustment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PD1Member" name="PD1Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PDGFRbetaoutsidetheUSMember" name="PDGFRbetaoutsidetheUSMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PaymentAxis" name="PaymentAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PaymentDomain" name="PaymentDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Paymentforpreferredshares" name="Paymentforpreferredshares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_PaymenttowardspurchasepriceofTarrytownfacility" name="PaymenttowardspurchasepriceofTarrytownfacility" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" name="PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfOutstandingSharesthattheCompanyisrequiredtoappointanindividualagreeduponbytheCompanyandtheCollaboratortotheCompanysboardofdirectors" name="PercentageOfOutstandingSharesthattheCompanyisrequiredtoappointanindividualagreeduponbytheCompanyandtheCollaboratortotheCompanysboardofdirectors" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByCollaboratingParty" name="PercentageOfTrialCostsBorneByCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByEntity" name="PercentageOfTrialCostsBorneByEntity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" name="PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofaggregatenetsalestobepaidbytherelatedpartyinsuchcalendaryear" name="Percentageofaggregatenetsalestobepaidbytherelatedpartyinsuchcalendaryear" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatespreviouslyrequiredtobepaidforunderthecollaboration" name="PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatespreviouslyrequiredtobepaidforunderthecollaboration" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofglobaldevelopmentcosttobepaidbythecollaborationpartnerunderthecollaboration" name="Percentageofglobaldevelopmentcosttobepaidbythecollaborationpartnerunderthecollaboration" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofrepaymentofdevelopmentbalanceoutofprofits" name="Percentageofrepaymentofdevelopmentbalanceoutofprofits" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" name="PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Periodoverwhichwehaveobligation" name="Periodoverwhichwehaveobligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Potentialextendedtermoflease" name="Potentialextendedtermoflease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PotentialfutureRDexpenses" name="PotentialfutureRDexpenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_ProductSalesandConcentrationRiskTextBlock" name="ProductSalesandConcentrationRiskTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ProvisionalchargeforremeasurementofU.S.deferredtaxassetsduetoUSTaxReform" name="ProvisionalchargeforremeasurementofU.S.deferredtaxassetsduetoUSTaxReform" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RebatesAndChargebacksMember" name="RebatesAndChargebacksMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReceivablesandRevenuesAbstract" name="ReceivablesandRevenuesAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RecognitionPeriodForAdvancePayment" name="RecognitionPeriodForAdvancePayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Reductionofnumberofwarrants" name="Reductionofnumberofwarrants" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ReimbursementreceivedbytheCompany" name="ReimbursementreceivedbytheCompany" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsAxis" name="ResearchCollaborationAndLicensingAgreementsAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsDomain" name="ResearchCollaborationAndLicensingAgreementsDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsLineItems" name="ResearchCollaborationAndLicensingArrangementsLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsTable" name="ResearchCollaborationAndLicensingArrangementsTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RevenueDisclosureTable" name="RevenueDisclosureTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenuebasedonpercentageofannualsalesinJapan" name="RevenuebasedonpercentageofannualsalesinJapan" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyRateMaximum" name="RoyaltyRateMaximum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyRateMinimum" name="RoyaltyRateMinimum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement100millionMemberMember" name="Salesachievement100millionMemberMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement1sttierMember" name="Salesachievement1sttierMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiMember" name="SanofiMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ScheduleOfFacilityLeasesLineItems" name="ScheduleOfFacilityLeasesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ScheduleOfFacilityLeasesTable" name="ScheduleOfFacilityLeasesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleofSelectedFinancialInformationBayerTableTextBlock" name="ScheduleofSelectedFinancialInformationBayerTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleofSelectedFinancialInformationSanofiTableTextBlock" name="ScheduleofSelectedFinancialInformationSanofiTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCollaboratingParty" name="ShareOfLossesOutsideUnitedStatesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCompany" name="ShareOfLossesOutsideUnitedStatesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived" name="Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Tarrytownfacilitycapitalandfacilityleaseobligations" name="Tarrytownfacilitycapitalandfacilityleaseobligations" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_TarrytownleaseAbstract" name="TarrytownleaseAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TarrytownleasetransactionMember" name="TarrytownleasetransactionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TechnologyLicensingAgreementsAbstract" name="TechnologyLicensingAgreementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TevaPharmaceuticalsMember" name="TevaPharmaceuticalsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_UnrestrictedMember" name="UnrestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_UpfrontPaymentMade" name="UpfrontPaymentMade" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
</xsd:schema>
