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	<footnotes>
		<footnote id="F1">On June 30, 2003 in relation to the elimination of Genzyme's tracking stock structure, all stock options of Genzyme Biosurgery and Genzyme Molecular were exchanged for stock options of Genzyme General.  The exchange ratio was based on the closing prices of all three stocks on 6/30/03.  Genzyme Biosurgery options were exchanged at a rate of .04945 and Genzyme Molecular Oncology options were exchanged at a rate of .05614.</footnote>
		<footnote id="F2">Options vest in 20% annual increments beginning 5/18/95.</footnote>
		<footnote id="F3">Options vest in 20% annual increments beginning 5/16/96.</footnote>
		<footnote id="F4">Options vest in 1/3 increments on December 8, 1994, March 14, 1996 and March 4, 1997</footnote>
		<footnote id="F5">Options vest in 20% annual increments beginning on the original date of grant.</footnote>
	</footnotes>
	<ownerSignature>
		<signatureName>By: Susan P. Cogswell, Attorney-in-Fact</signatureName>
		<signatureDate>2003-07-02</signatureDate>
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X0101
4
2003-06-30
0
0000732485
GENZYME CORP
GENZ
0001021037
SMITH ALAN E
0
1
0
0
Senior Vice President
Biosurgery ISO stock option (right to buy)
17.90
2003-06-30
4
J
0
1709
0
D
1995-05-18
2005-05-18
Genzyme Biosurgery common stock (GZBX)
1709
0
D
Biosurgery ISO stock option (right to buy)
36.55
2003-06-30
4
J
0
1709
0
D
1996-05-16
2006-05-16
Genzyme Biosurgery common stock (GZBX)
1709
0
D
Biosurgery NQ stock option (right to buy)
15.12
2003-06-30
4
J
0
1131
0
D
2003-06-30
2003-12-08
Genzyme Biosurgery common stock (GZBX)
1131
0
D
Biosurgery NQ stock option (right to buy)
15.30
2003-06-30
4
J
0
384
0
D
1994-05-19
2004-05-19
Genzyme Biosurgery common stock (GZBX)
384
0
D
Biosurgery NQ stock option (right to buy)
14.10
2003-06-30
4
J
0
452
0
D
1994-12-08
2004-12-08
Genzyme Biosurgery common stock (GZBX)
452
0
D
Genzyme General ISO stock option (right to buy)
361.99
2003-06-30
4
J
0
84
0
A
1995-05-18
2005-05-18
Genzyme General common stock (GENZ)
84
84
D
Genzyme General ISO stock option (right to buy)
739.13
2003-06-30
4
J
0
84
0
A
1996-06-16
2006-05-16
Genzyme General common stock (GENZ)
84
84
D
Genzyme General NQ stock option (right to buy)
305.77
2003-06-30
4
J
0
55
0
A
2003-06-30
2003-12-08
Genzyme General common stock (GENZ)
55
55
D
Genzyme General NQ stock option (right to buy)
309.41
2003-06-30
4
J
0
18
0
A
1994-05-19
2004-05-19
Genzyme General common stock (GENZ)
18
18
D
Genzyme General NQ stock option (right to buy)
285.14
2003-06-30
4
J
0
22
0
A
1994-12-08
2004-12-08
Genzyme General common stock (GENZ)
22
22
D
On June 30, 2003 in relation to the elimination of Genzyme's tracking stock structure, all stock options of Genzyme Biosurgery and Genzyme Molecular were exchanged for stock options of Genzyme General.  The exchange ratio was based on the closing prices of all three stocks on 6/30/03.  Genzyme Biosurgery options were exchanged at a rate of .04945 and Genzyme Molecular Oncology options were exchanged at a rate of .05614.
Options vest in 20% annual increments beginning 5/18/95.
Options vest in 20% annual increments beginning 5/16/96.
Options vest in 1/3 increments on December 8, 1994, March 14, 1996 and March 4, 1997
Options vest in 20% annual increments beginning on the original date of grant.
By: Susan P. Cogswell, Attorney-in-Fact
2003-07-02