- Annual Statement of Changes in Beneficial Ownership (5)

FORM 5

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
[ ] Form 3 Holdings Reported
[ X ] Form 4 Transactions Reported

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

ANNUAL STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

OMB APPROVAL
OMB Number: 3235-0362
Expires: February 28, 2011
Estimated average burden
hours per response... 1.0

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public
Utility Holding Company Act of 1935 or Section 30(f) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* Amello Jason	2. Issuer Name and Ticker or Trading Symbol GENZYME CORP [GENZ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __ X __ Officer (give title below) _____ Other (specify below) CorpContrllr,ChiefAccntOfficer
(Last) (First) (Middle) 500 KENDALL STREET	3. Statement for Issuer's Fiscal Year Ended (MM/DD/YYYY) 12/31/2010
(Street) CAMBRIDGE, MA 02142 (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form Filed by One Reporting Person ___ Form Filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)	4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Genzyme common stock (GENZ)	7/23/2010		S	595.0000	D	$62.9500	2675.0000 ⁽¹⁾	D
Genzyme common stock (GENZ)	7/26/2010		S	1042.0000	D	$65.2500	1633.0000 ⁽²⁾	D
Genzyme common stock (GENZ)	8/31/2010		M4	6640.0000	A	$46.2400	1633.0000	D

*Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)	5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (MM/DD/YYYY)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of Derivative Securities Beneficially Owned at End of Issuer's Fiscal Year (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$46.2400	8/31/2010		M4		6640.0000	5/29/2003	5/29/2013	Genzyme common stock (GENZ)	6640.0000	$46.2400	0.0000	D

Explanation of Responses:
( 1)	Transaction reported late for Form 4 filing that was due on July 27, 2010.
( 2)	Transaction reported late for Form 4 filing that was due on July 28, 2010.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
Amello Jason 500 KENDALL STREET CAMBRIDGE, MA 02142			CorpContrllr,ChiefAccntOfficer

Signatures
Susan P. Cogswell, Attorney-in-Fact		2/10/2011
^** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.