FORM 4
[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
OMB APPROVAL
OMB Number: 3235-0287
Expires: February 28, 2011
Estimated average burden
hours per response... 0.5
                      
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 *

BERTHIAUME DOUGLAS A 		2. Issuer Name and Ticker or Trading Symbol

GENZYME CORP [ GENZ ] 		5. Relationship of Reporting Person(s) to Issuer (Check all applicable)

__ X __ Director                      _____ 10% Owner
_____ Officer (give title below)      _____ Other (specify below)
(Last)          (First)          (Middle)

500 KENDALL STREET 		3. Date of Earliest Transaction (MM/DD/YYYY)

4/4/2011
(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)
Code V Amount (A) or (D) Price
Genzyme common stock (GENZ)   4/4/2011     M    2375.0000   A $0.0000   73533.0000   D    
Genzyme common stock (GENZ)   4/4/2011     M    949.9060   A $0   (1) 74482.9060   D    
Genzyme common stock (GENZ)   4/4/2011     M    609.9520   A $0   (1) 75092.8580   D    
Genzyme common stock (GENZ)   4/4/2011     M    511.4740   A $0   (1) 75604.3320   D    
Genzyme common stock (GENZ)   4/4/2011     M    445.1490   A $0   (1) 76049.4810   D    
Genzyme common stock (GENZ)   4/4/2011     M    430.3220   A $0   (1) 76479.8030   D    
Genzyme common stock (GENZ)   4/4/2011     M    419.9370   A $0   (1) 76899.7400   D    
Genzyme common stock (GENZ)   4/4/2011     M    406.7110   A $0   (1) 77306.4510   D    
Genzyme common stock (GENZ)   4/4/2011     M    405.7100   A $0   (1) 77712.1610   D    
Genzyme common stock (GENZ)   4/4/2011     M    391.9930   A $0   (1) 78104.1540   D    
Genzyme common stock (GENZ)   4/4/2011     M    368.9370   A $0   (1) 78473.0910   D    
Genzyme common stock (GENZ)   4/4/2011     M    322.9000   A $0   (1) 78795.9910   D    
Genzyme common stock (GENZ)   4/4/2011     M    318.3280   A $0   (1) 79114.3190   D    
Genzyme common stock (GENZ)   4/4/2011     M    314.6960   A $0   (1) 79429.0150   D    
Genzyme common stock (GENZ)   4/4/2011     M    292.7520   A $0   (1) 79721.7670   D    
Genzyme common stock (GENZ)   4/4/2011     M    286.4980   A $0   (1) 80008.2650   D    
Genzyme common stock (GENZ)   4/4/2011     M    274.7090   A $0   (1) 80282.9740   D    
Genzyme common stock (GENZ)   4/4/2011     M    266.9520   A $0   (1) 80549.9260   D    
Genzyme common stock (GENZ)   4/4/2011     M    262.3920   A $0   (1) 80812.3180   D    
Genzyme common stock (GENZ)   4/4/2011     M    254.7720   A $0   (1) 81067.0900   D    
Genzyme common stock (GENZ)   4/4/2011     M    233.4010   A $0   (1) 81300.4910   D    
Genzyme common stock (GENZ)   4/4/2011     M    230.1370   A $0   (1) 81530.6280   D    
Genzyme common stock (GENZ)   4/4/2011     M    224.0250   A $0   (1) 81754.6530   D    
Genzyme common stock (GENZ)   4/4/2011     M    211.1210   A $0   (1) 81965.7740   D    
Genzyme common stock (GENZ)   4/4/2011     M    208.5310   A $0   (1) 82174.3050   D    
Genzyme common stock (GENZ)   4/4/2011     M    188.5800   A $0   (1) 82362.8850   D    
Genzyme common stock (GENZ)   4/4/2011     M    175.9750   A $0   (1) 82538.8600   D    
Genzyme common stock (GENZ)   4/4/2011     D    2375.0000   D $74.0000   80163.8600   D    
Genzyme common stock (GENZ)   4/4/2011     D    9005.8600   D $76.0100   71158.0000   D    
Genzyme common stock (GENZ)   4/4/2011     U    71158.0000   D $74.0000   0.0000   D    

Table II - Derivative Securities 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 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 Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Phantom Stock     (1) 4/4/2011     M         254.7720    3/31/2005   (1) 12/31/2034   Genzyme common stock (GENZ)   254.7720   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         211.1210    3/31/2006   (1) 12/31/2034   Genzyme common stock (GENZ)   211.1210   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         286.4980    3/31/2007   (1) 12/31/2034   Genzyme common stock (GENZ)   286.4980   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         314.6960    3/31/2008   (1) 12/31/2034   Genzyme common stock (GENZ)   314.6960   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         405.7100    3/31/2009   (1) 12/31/2034   Genzyme common stock (GENZ)   405.7100   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         511.4740    3/31/2010   (1)   (1) Genzyme common stock (GENZ)   511.4740   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         274.7090    6/30/2004   (1) 12/20/2034   Genzyme common stock (GENZ)   274.7090   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         208.5310    6/30/2005   (1) 12/31/2034   Genzyme common stock (GENZ)   208.5310   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         266.9520    6/30/2006   (1) 12/31/2034   Genzyme common stock (GENZ)   266.9520   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         230.1370    6/30/2007   (1) 12/31/2034   Genzyme common stock (GENZ)   230.1370   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         368.9370    6/30/2008   (1) 12/31/2034   Genzyme common stock (GENZ)   368.9370   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         430.3220    6/30/2009   (1)   (1) Genzyme common stock (GENZ)   430.3220   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         949.9060    6/30/2010   (1)   (1) Genzyme common stock (GENZ)   949.9060   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         188.5800    9/30/2004   (1) 12/31/2034   Genzyme common stock (GENZ)   188.5800   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         175.9750    9/30/2005   (1) 12/31/2034   Genzyme common stock (GENZ)   175.9750   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         224.0250    9/30/2006   (1) 12/31/2034   Genzyme common stock (GENZ)   224.0250   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         318.3280    9/30/2007   (1) 12/31/2034   Genzyme common stock (GENZ)   318.3280   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         262.3920    9/30/2008   (1) 12/31/2034   Genzyme common stock (GENZ)   262.3920   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         406.7110    9/30/2009   (1)   (1) Genzyme common stock (GENZ)   406.7110   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         233.4010    12/31/2004   (1) 12/31/2034   Genzyme common stock (GENZ)   233.4010   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         292.7520    12/31/2005   (1) 12/31/2034   Genzyme common stock (GENZ)   292.7520   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         445.1490    12/31/2006   (1) 12/31/2034   Genzyme common stock (GENZ)   445.1490   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         391.9930    12/31/2007   (1) 12/31/2034   Genzyme common stock (GENZ)   391.9930   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         419.9370    12/31/2008   (1) 12/31/2034   Genzyme common stock (GENZ)   419.9370   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         609.9520    12/31/2009   (1)   (1) Genzyme common stock (GENZ)   609.9520   $0.0000   0.0000   D    
Phantom Stock     (1) 4/4/2011     M         322.9000    12/31/2010   (1)   (1) Genzyme common stock (GENZ)   322.9000   $0.0000   0.0000   D    
Restricted Stock Units   $0.0000   4/4/2011     M         2375.0000      (2)   (2) Genzyme common stock (GENZ)   2375.0000   $0.0000   0.0000   D    
Stock Option (right to buy)   $51.5200   4/4/2011     D         7125.0000      (3) 6/16/2020   Genzyme common stock (GENZ)   7125.0000   $51.5200   0.0000   D    
Stock Option (right to buy)   $43.9000   4/4/2011     D         15000.0000    5/27/2005   (3) 5/27/2014   Genzyme common stock (GENZ)   15000.0000   $43.9000   0.0000   D    
Stock Option (right to buy)   $53.4700   4/4/2011     D         18000.0000    5/31/2002   (3) 5/31/2011   Genzyme common stock (GENZ)   18000.0000   $53.4700   0.0000   D    

Explanation of Responses:
( 1)  The phantom stock acquired under the Genzyme Directors? Deferred Compensation Plan was cancelled at the completion of the sanofi-aventis tender offer and converted into the right to receive a cash payment based on the closing price of Genzyme common stock on the last day it traded. Phantom stock was credited to the Reporting Person?s stock account under the deferred compensation at the end of each fiscal quarter from Apiril 1, 2004 through December 31, 2010, pursuant to the Reporting Person?s plan election and the terms of the plan.
( 2)  The vested restricted stock units were scheduled to vest on the date of the 2011 annual meeting of shareholders.
( 3)  This option, which provided for vesting at the next annual meeting of shareholders, was cancelled upon the consummation of the sanofi-aventis tender offer in exchange for a payment representing (A) an amount of cash equal to the excess of $74.00 over the exercise price of the option, multiplied by the total number of shares subject to such options, and (B) one contingent value right (CVR) per cancelled option.

Remarks:
,Multiple Forms Submitted

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
BERTHIAUME DOUGLAS A
500 KENDALL STREET
CAMBRIDGE, MA 02142 		X



Signatures
Susan P. Cogswell, Attorney-in-Fact 4/6/2011
** 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.
Genzyme (NASDAQ:GENZ)
Historical Stock Chart
From Apr 2024 to May 2024 Click Here for more Genzyme Charts.
Genzyme (NASDAQ:GENZ)
Historical Stock Chart
From May 2023 to May 2024 Click Here for more Genzyme Charts.