<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
	<periodOfReport>2003-09-02</periodOfReport>
	<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000732485</issuerCik>
        <issuerName>GENZYME CORP</issuerName>
        <issuerTradingSymbol>GENZ</issuerTradingSymbol>
	</issuer>
	<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001021040</rptOwnerCik>
            <rptOwnerName>VAN HEEK G JAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GENZYME CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>ONE KENDALL SQUARE</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>021391562</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
			<isDirector>0</isDirector>
			<isOfficer>1</isOfficer>
			<isTenPercentOwner>0</isTenPercentOwner>
			<isOther>0</isOther>
			<officerTitle>Executive Vice President</officerTitle>
		</reportingOwnerRelationship>
	</reportingOwner>
	<nonDerivativeTable>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>M</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>25000</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>7.27</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>A</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>28514</value>
					<footnoteId id="F2"/>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>6000</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.15</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>22514</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>1200</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.19</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>21314</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>2008</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.23</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>19306</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>300</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.28</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>19006</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>14671</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.29</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>4335</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>621</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.32</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>3714</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeTransaction>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>S</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
				<footnoteId id="F1"/>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>200</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>47.34</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>3514</value>
					<footnoteId id="F2"/>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeTransaction>
		<nonDerivativeHolding>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>816</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>I</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value>By 401(k)</value>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeHolding>
		<nonDerivativeHolding>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>1665</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>I</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value>By 401(k) by spouse</value>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeHolding>
		<nonDerivativeHolding>
			<securityTitle>
				<value>Genzyme General common stock (GENZ)</value>
			</securityTitle>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>4341</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>I</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value>By Spouse</value>
				</natureOfOwnership>
			</ownershipNature>
		</nonDerivativeHolding>
	</nonDerivativeTable>
	<derivativeTable>
		<derivativeTransaction>
			<securityTitle>
				<value>Genzyme General NQ stock option (right to buy)</value>
			</securityTitle>
			<conversionOrExercisePrice>
				<value>7.27</value>
			</conversionOrExercisePrice>
			<transactionDate>
				<value>2003-09-02</value>
			</transactionDate>
			<deemedExecutionDate>
				<value>2003-09-02</value>
			</deemedExecutionDate>
			<transactionCoding>
				<transactionFormType>4</transactionFormType>
				<transactionCode>M</transactionCode>
				<equitySwapInvolved>0</equitySwapInvolved>
			</transactionCoding>
			<transactionAmounts>
				<transactionShares>
					<value>25000</value>
				</transactionShares>
				<transactionPricePerShare>
					<value>0</value>
				</transactionPricePerShare>
				<transactionAcquiredDisposedCode>
					<value>D</value>
				</transactionAcquiredDisposedCode>
			</transactionAmounts>
			<exerciseDate>
				<value>2003-06-30</value>
			</exerciseDate>
			<expirationDate>
				<value>2003-12-08</value>
			</expirationDate>
			<underlyingSecurity>
				<underlyingSecurityTitle>
					<value>Genzyme General common stock (GENZ)</value>
				</underlyingSecurityTitle>
				<underlyingSecurityShares>
					<value>25000</value>
				</underlyingSecurityShares>
			</underlyingSecurity>
			<postTransactionAmounts>
				<sharesOwnedFollowingTransaction>
					<value>25000</value>
				</sharesOwnedFollowingTransaction>
			</postTransactionAmounts>
			<ownershipNature>
				<directOrIndirectOwnership>
					<value>D</value>
				</directOrIndirectOwnership>
				<natureOfOwnership>
					<value/>
				</natureOfOwnership>
			</ownershipNature>
		</derivativeTransaction>
	</derivativeTable>
	<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">The exercise of this stock option included a distribution of an additional 5 shares of Genzyme common stock.  These stock options were entitled to receive a distribution of shares of Tissue Repair common stock that was paid on July 22, 1997 to Genzyme General Division stockholders at a rate of 0.015.  In connection with the formation of Genzyme Biosurgery in December 2000, shares of Genzyme Tissue Repair were converted into shares of Genzyme Biosurgery at a rate of 0.3352.  In connection with the exchange of Genzyme Biosurgery stock into Genzyme General stock on June 30, 2003, distributions of the Genzyme Biosurgery stock are exchanged into Genzyme General stock at a rate of 0.04945.</footnote>
	</footnotes>
	<remarks>
	</remarks>
	<ownerSignature>
		<signatureName>By: Susan P. Cogswell, Attorney-in-Fact</signatureName>
		<signatureDate>2002-09-03</signatureDate>
	</ownerSignature>
</ownershipDocument>
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X0201
4
2003-09-02
0
0000732485
GENZYME CORP
GENZ
0001021040
VAN HEEK G JAN
GENZYME CORPORATION
ONE KENDALL SQUARE
CAMBRIDGE
MA
021391562
0
1
0
0
Executive Vice President
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
M
0
25000
7.27
A
28514
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
6000
47.15
D
22514
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
1200
47.19
D
21314
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
2008
47.23
D
19306
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
300
47.28
D
19006
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
14671
47.29
D
4335
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
621
47.32
D
3714
D
Genzyme General common stock (GENZ)
2003-09-02
2003-09-02
4
S
0
200
47.34
D
3514
D
Genzyme General common stock (GENZ)
816
I
By 401(k)
Genzyme General common stock (GENZ)
1665
I
By 401(k) by spouse
Genzyme General common stock (GENZ)
4341
I
By Spouse
Genzyme General NQ stock option (right to buy)
7.27
2003-09-02
2003-09-02
4
M
0
25000
0
D
2003-06-30
2003-12-08
Genzyme General common stock (GENZ)
25000
25000
D
The sales reported were effected pursuant to a Rule 10b5-1 trading plan adpoted by the reporting person on June 16, 2003.
The exercise of this stock option included a distribution of an additional 5 shares of Genzyme common stock.  These stock options were entitled to receive a distribution of shares of Tissue Repair common stock that was paid on July 22, 1997 to Genzyme General Division stockholders at a rate of 0.015.  In connection with the formation of Genzyme Biosurgery in December 2000, shares of Genzyme Tissue Repair were converted into shares of Genzyme Biosurgery at a rate of 0.3352.  In connection with the exchange of Genzyme Biosurgery stock into Genzyme General stock on June 30, 2003, distributions of the Genzyme Biosurgery stock are exchanged into Genzyme General stock at a rate of 0.04945.
By: Susan P. Cogswell, Attorney-in-Fact
2002-09-03