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	<footnotes>
		<footnote id="F1">The sales reported were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 28, 2003.</footnote>
		<footnote id="F2">Includes 1,053 shares purchased from the issuer's Employee Stock Purchase Plan on July 9, 2003.</footnote>
		<footnote id="F3">The exercise of this stock option included a distribution of an additional 4 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>
		<footnote id="F4">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>2003-07-21</signatureDate>
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0000732485
GENZYME CORP
GENZ
0001021029
MOSCICKI RICHARD A
0
1
0
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Senior Vice President
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Genzyme General common stock (GENZ)
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14788
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Genzyme General common stock (GENZ)
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2003-07-17
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S
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Genzyme General common stock (GENZ)
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2003-07-17
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D
11288
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
300
48.05
D
10988
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
500
48.12
D
10488
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
208
48.17
D
10280
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
300
48.20
D
9980
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
100
48.19
D
9880
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
100
48.21
D
9780
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
1000
48.22
D
8780
D
Genzyme General common stock (GENZ)
2003-07-17
2003-07-17
4
S
0
1892
48.23
D
6888
D
Genzyme General NQ stock option (right to buy)
43.30
2003-07-10
4
A
0
10000
0
A
2003-07-10
2013-07-10
Genzyme General common stock (GENZ)
10000
10000
D
Genzyme General NQ stock option (right to buy)
7.27
2003-07-17
2003-07-17
4
M
0
20000
0
D
2003-06-30
2003-12-08
Genzyme General common stock (GENZ)
20000
60000
D
The sales reported were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 28, 2003.
Includes 1,053 shares purchased from the issuer's Employee Stock Purchase Plan on July 9, 2003.
The exercise of this stock option included a distribution of an additional 4 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.
Options vest in 20% annual increments beginning on the original date of grant.
By: Susan P. Cogswell, Attorney-in-Fact
2003-07-21