-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 U7yv0O8MIvokC8kTRy2q/6w1Sy3aWTAH7bkIxrb3anwHFY6RngLdtf0Oueb8gxhj
 FYspePUIYCaNKzu8zWhPrw==

<SEC-DOCUMENT>0001005477-03-001497.txt : 20030521
<SEC-HEADER>0001005477-03-001497.hdr.sgml : 20030521
<ACCEPTANCE-DATETIME>20030521144534
ACCESSION NUMBER:		0001005477-03-001497
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030513
FILED AS OF DATE:		20030521

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			REGENERON PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0000872589
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				133444607
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		777 OLD SAW MILL RIVER RD
		CITY:			TARRYTOWN
		STATE:			NY
		ZIP:			10591-6707
		BUSINESS PHONE:		9143477000

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NOVARTIS INC
		CENTRAL INDEX KEY:			0001030617

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19034
		FILM NUMBER:		03714390

	BUSINESS ADDRESS:	
		STREET 1:		SCHWARZWALDALLEE 215
		STREET 2:		4002 BASEL
		CITY:			SWITZERLAND
		BUSINESS PHONE:		2128302413

	MAIL ADDRESS:	
		STREET 1:		SCHWARZWALDALLEE 215
		STREET 2:		4002 BASEL
		CITY:			SWITZERLAND
		STATE:			V8
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar123.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0101</schemaVersion>

    <documentType>3</documentType>
    <periodOfReport>2003-05-13</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000872589</issuerCik>
        <issuerName>REGENERON PHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>REGN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
    <reportingOwnerId>
            <rptOwnerCik>0001030617</rptOwnerCik>
            <rptOwnerName>NOVARTIS INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
        <isDirector>0</isDirector>
        <isOfficer>0</isOfficer>
        <isTenPercentOwner>1</isTenPercentOwner>
        <isOther>0</isOther>
    </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionAmounts>
            <transactionShares>
                <value>7527050</value>
            </transactionShares>
        </transactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <ownerSignature>
        <signatureName>Joseph  E. Mamie / Kimbely Urdahl</signatureName>
        <signatureDate>2003-05-21</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----