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  <xsd:element abstract="true" id="regn_ClassificationOfInvestmentAxis" name="ClassificationOfInvestmentAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ClassificationOfInvestmentDomain" name="ClassificationOfInvestmentDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_CollaborationAgreementAbstract" name="CollaborationAgreementAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_CollaborationAgreementWithBayerHealthcareLlcMember" name="CollaborationAgreementWithBayerHealthcareLlcMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_CollaborationRevenueTableTextBlock" name="CollaborationRevenueTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Collaborationrevenue" name="Collaborationrevenue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_CollaborativeArrangementAdditionalEligibleAggregatePayments" name="CollaborativeArrangementAdditionalEligibleAggregatePayments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Costofmanufacturing" name="Costofmanufacturing" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_CurascriptSDMember" name="CurascriptSDMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_DeferredRevenueFromRelatedParty" name="DeferredRevenueFromRelatedParty" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_DeferredRevenueFromRelatedPartyCurrent" name="DeferredRevenueFromRelatedPartyCurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_DeferredRevenueFromRelatedPartyNoncurrent" name="DeferredRevenueFromRelatedPartyNoncurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <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_EyleaNetProductSalesMember" name="EyleaNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <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_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Licenseagreementterm" name="Licenseagreementterm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" 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_Maximumamountofshareddevelopmentcosts" name="Maximumamountofshareddevelopmentcosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <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_Netprofitlossfromcommercializationofproductsundercollaborationagreement" name="Netprofitlossfromcommercializationofproductsundercollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" 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_OtherSalesRelatedDeductionsMember" name="OtherSalesRelatedDeductionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" 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 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_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PraluentKevzaraandDupixentMemberMember" name="PraluentKevzaraandDupixentMemberMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" 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_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_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_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_ScheduleofSelectedFinancialInformationTevaTableTextBlock" name="ScheduleofSelectedFinancialInformationTevaTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleofSelectedFinancialinformationIOTableTextBlock" name="ScheduleofSelectedFinancialinformationIOTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" 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_Upfrontpaymentreceived" name="Upfrontpaymentreceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
</xsd:schema>
