<SEC-DOCUMENT>0001181431-11-022768.txt : 20110406
<SEC-HEADER>0001181431-11-022768.hdr.sgml : 20110406
<ACCEPTANCE-DATETIME>20110406161133
ACCESSION NUMBER:		0001181431-11-022768
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20110405
FILED AS OF DATE:		20110406
DATE AS OF CHANGE:		20110406

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:		500 KENDALL STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		6172527500

	MAIL ADDRESS:	
		STREET 1:		500 KENDALL STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SANOFI-AVENTIS
		CENTRAL INDEX KEY:			0001121404
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		STATE OF INCORPORATION:			I0
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14680
		FILM NUMBER:		11743334

	BUSINESS ADDRESS:	
		STREET 1:		174 AVENUE DE FRANCE
		CITY:			PARIS
		STATE:			I0
		ZIP:			75013
		BUSINESS PHONE:		33153774400

	MAIL ADDRESS:	
		STREET 1:		174 AVENUE DE FRANCE
		CITY:			PARIS
		STATE:			I0
		ZIP:			75013

	FORMER NAME:	
		FORMER CONFORMED NAME:	SANOFI SYNTHELABO SA
		DATE OF NAME CHANGE:	20010104

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GC Merger Corp.
		CENTRAL INDEX KEY:			0001501770
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14680
		FILM NUMBER:		11743333

	BUSINESS ADDRESS:	
		STREET 1:		C/O SANOFI-AVENTIS
		STREET 2:		270 ALABANY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		011 33 1 53 77 48 96

	MAIL ADDRESS:	
		STREET 1:		C/O SANOFI-AVENTIS
		STREET 2:		270 ALABANY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>rrd307920.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2011-04-05</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000732485</issuerCik>
        <issuerName>GENZYME CORP</issuerName>
        <issuerTradingSymbol>GENZ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001121404</rptOwnerCik>
            <rptOwnerName>SANOFI-AVENTIS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>174, AVENUE DE FRANCE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PARIS</rptOwnerCity>
            <rptOwnerState>I0</rptOwnerState>
            <rptOwnerZipCode>75013</rptOwnerZipCode>
            <rptOwnerStateDescription>FRANCE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001501770</rptOwnerCik>
            <rptOwnerName>GC Merger Corp.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>55 CORPORATE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BRIDGEWATER</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08807</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, $0.01 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>184038545</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By GC Merger Corp.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Reflects shares exchanged in an exchange offer.</footnote>
        <footnote id="F2">The shares are held by GC Merger Corp. (the &quot;Purchaser&quot;).  The Purchaser is direct wholly-owned subsidiary of sanofi-aventis (&quot;Parent&quot;) and is the owner of the shares purchased in the exchange offer.  The shares may also be deemed to be indirectly beneficially owned by Parent.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ SEE EXHIBIT 99.1</signatureName>
        <signatureDate>2011-04-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>2
<FILENAME>rrd276139_311642.htm
<DESCRIPTION>EXHIBIT
<TEXT>
<HTML>
<HEAD>
<TITLE>
rrd276139_311642.html
</TITLE>
</HEAD>
<BODY>
<PRE>
                                                                    EXHIBIT 99.1

                              SIGNATURES FOR FORM 3

                                 SANOFI-AVENTIS

                                 By: /s/ John Felitti
                                     ------------------------------------------
                                 Name: John Felitti
                                 Title: Associate Vice President, Corporate Law,
                                 Financial & Securities Law
                                 Date: 04/06/2011


                                 GC Merger Corp.

                                 By: /s/ Gregory Irace
                                     ------------------------------------------
                                 Name: Gregory Irace
                                 Title: President
                                 Date: 04/06/2011
</PRE>
</BODY>
</HTML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
