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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 AIBGChg6I4+fJbsO0rS6FLx/XfM12pDIRb8V1PGbxC/ca0pkVBEZ6QtcpT378n+A
 fJLaQ0jW+toiUSOO2FILwA==

<SEC-DOCUMENT>0000732485-03-000032.txt : 20030724
<SEC-HEADER>0000732485-03-000032.hdr.sgml : 20030724
<ACCEPTANCE-DATETIME>20030724123632
ACCESSION NUMBER:		0000732485-03-000032
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030723
FILED AS OF DATE:		20030724

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GENZYME CORP
		CENTRAL INDEX KEY:			0000732485
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				061047163
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ONE KENDALL SQ
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		6172527500

	MAIL ADDRESS:	
		STREET 1:		ONE KENDALL SQUARE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			WIRTH PETER
		CENTRAL INDEX KEY:			0001021041
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14680
		FILM NUMBER:		03800338

	BUSINESS ADDRESS:	
		STREET 1:		C/O GENZYME CORP
		STREET 2:		ONE KENDALL SQ
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		6172527500

	MAIL ADDRESS:	
		STREET 1:		ONE KENDALL SQUARE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wir62.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
	<periodOfReport>2003-07-23</periodOfReport>
	<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000732485</issuerCik>
        <issuerName>GENZYME CORP</issuerName>
        <issuerTradingSymbol>GENZ</issuerTradingSymbol>
	</issuer>
	<reportingOwner>
		<reportingOwnerId>
            <rptOwnerCik>0001021041</rptOwnerCik>
            <rptOwnerName>WIRTH PETER</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
			<isDirector>0</isDirector>
			<isOfficer>1</isOfficer>
			<isTenPercentOwner>0</isTenPercentOwner>
			<isOther>0</isOther>
			<officerTitle>Executive Vice President</officerTitle>
		</reportingOwnerRelationship>
	</reportingOwner>
	<nonDerivativeSecurity>
		<securityTitle>
			<value>Genzyme General common stock (GENZ)</value>
		</securityTitle>
		<transactionDate>
			<value>2003-07-23</value>
		</transactionDate>
		<deemedExecutionDate>
			<value>2003-07-23</value>
		</deemedExecutionDate>
		<transactionCoding>
			<transactionFormType>4</transactionFormType>
			<transactionCode>S</transactionCode>
			<equitySwapInvolved>0</equitySwapInvolved>
			<footnoteId id="F1"/>
		</transactionCoding>
		<transactionAmounts>
			<transactionShares>
				<value>34320</value>
			</transactionShares>
			<transactionValue>
				<value>50.01</value>
			</transactionValue>
			<transactionAcquiredDisposedCode>
				<value>D</value>
			</transactionAcquiredDisposedCode>
		</transactionAmounts>
		<postTransactionAmounts>
			<sharesOwnedFollowingTransaction>
				<value>7761</value>
				<footnoteId id="F2"/>
			</sharesOwnedFollowingTransaction>
		</postTransactionAmounts>
		<ownershipNature>
			<directOrIndirectOwnership>
				<value>D</value>
			</directOrIndirectOwnership>
			<natureOfOwnership>
				<value/>
			</natureOfOwnership>
		</ownershipNature>
	</nonDerivativeSecurity>
	<footnotes>
		<footnote id="F1">The sales reported were effected pursuant to a Rule 10b5-1 trading plan adpoted by the reporting person on June 16, 2003.</footnote>
		<footnote id="F2">Includes 421 shares purchased from the issuer's Employee Stock Purchase Plan on July 9, 2003.</footnote>
	</footnotes>
	<ownerSignature>
		<signatureName>By: Susan P. Cogswell, Attorney-in-Fact</signatureName>
		<signatureDate>2003-07-23</signatureDate>
	</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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