Form 425

Filed by sanofi-aventis

Pursuant to Rule 425 under the Securities Act of 1933, as amended

Subject Company: Genzyme Corporation

Exchange Act Commission File No: 0-14680

The following is a presentation delivered at a town hall meeting held by Genzyme Corporation (“Genzyme”) for Genzyme employees on February 16, 2011, in connection with the Agreement and Plan of Merger, dated as of February 16, 2011, among sanofi-aventis, GC Merger Corp. and Genzyme.


Sanofi-aventis
Town hall meeting
February 16
th
, 2011


Forward-Looking Statements
Important Information about this Transaction
This communication is neither an offer to purchase nor a solicitation of any offer to sell any securities.  In connection with the proposed
transaction, sanofi-aventis will file an amended tender offer statement and a registration statement on Form F-4 to register certain securities and
certain related documents and Genzyme will file a Solicitation/Recommendation Statement with respect to the exchange offer with the U.S.
Securities and Exchange Commission (the “SEC”). Genzyme shareholders are urged to read the registration statement and exchange offer
documents when they become available because they will contain important information that shareholders should consider before making any
decision regarding tendering their shares.  These documents will be mailed to all Genzyme shareholders of record.  These documents, as they
may be amended from time to time, contain important information about the proposed transaction and Genzyme shareholders are urged to read
them carefully and in their entirety before any decision is made with respect to the proposed transaction.  When available, documentation relating
to the transaction may be obtained at no charge at the website maintained by the SEC at www.sec.gov and may also be obtained at no charge by
directing a request by mail to MacKenzie Partners, Inc., 105 Madison Avenue, New York, New York 10016, or by calling toll-free at (800) 322-
2885.  Free copies of the Solicitation/Recommendation Statement will be made available by Genzyme; investors and security holders can obtain
free copies of these documents from Genzyme by directing a request to Genzyme at 500 Kendall Street, Cambridge, MA 02142, Attention:
Shareholder Relations Department, or by calling 617-252-7500 and asking for the Shareholder Relations Department.
This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities
in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any
such jurisdiction.  No offering of securities shall be made except by means of a prospectus meeting the requirements of the U.S. Securities Act of
1933, as amended, or an exemption therefrom.
Forward-Looking Statements
Any statements made in this communication that are not statements of historical fact, including statements about sanofi-aventis' beliefs and
expectations and statements about the acquisition of Genzyme, are forward-looking statements and should be evaluated as such.  Forward-
looking statements include statements that may relate to sanofi-aventis' plans, objectives, strategies, goals, future events, future revenues or
performance, and other information that is not historical information.  Factors that may materially affect such forward-looking statements include:
the risk that the acquisition of Genzyme may not be consummated for reasons including that the conditions precedent to the completion of the
acquisition may not be satisfied; the possibility that the expected benefits from the proposed transaction will not be realized, or will not be realized
within the anticipated time period; the risk that sanofi-aventis' and Genzyme's businesses will not be integrated successfully; the possibility of
disruption from the acquisition making it more difficult to maintain business and operational relationships; any actions taken by either of the
companies, including but not limited to, restructuring or strategic initiatives (including capital investments or asset acquisitions or dispositions). 
Sanofi-aventis does not undertake, and specifically disclaims, any obligation or responsibility to update or amend any of the information above
except as otherwise required by law.


Worldwide presence
(1) US + Canada + Porto Rico
(2) Western Europe + Eastern Europe + Turkey
(3) Australia + New Zealand
All results based on Press Release Feb 9th 2011
North America
15 106
employees
9, 484M€
(1)
Europe
54 815
employees
11,609M€
(2)
Japan
3 153 employees
2,225M€
Africa/Middle East
4 529 employees
Africa:
846M€
Middle East:
789M€
Latin America
8 891 employees
2,735M€
Asia-Pacific
15 081 employees
Asia:
1,983M€
Pacific
(3)
:
713M


30,384
Sanofi-aventis -
A world leader
30,384 m
2010 NET SALES-GROSS OF 3,7%
COMPARED WITH 2009
ON A REPORTED BASIS
100,000
More than
100,000
EMPLOYEES WORLDWIDE
1
ONE
OF THE LARGEST
PHARMACEUTICAL
GROUPS IN THE WORLD


Achieving our ambition through core growth platforms
Growth platforms
Diabetes
Vaccines
Emerging Markets
Consumer Health Care
Innovative Products
Animal Health
-
A global sustainable healthcare partner focused on patients’
needs
-
Recognised
for our ability to transform scientific innovation into
hope and solutions for patients


Diabetes
Oncology
Cardiovascular
Atrial Fibrillation
Vaccines
Consumer
Heath Care
Our response to health issues


Our culture
CONFIDENCE
INNOVATION
RESPECT
SOLIDARITY
INTEGRITY


Town hall meeting
February 16
th
, 2011


General principles for working together
Acknowledge and recognize your unique know-how and build on your DNA
Genzyme brand
Greater Boston Area
Listen to you, understand your business and create a collaborative spirit to
take this forward together
Focus on the day-to-day business and continue to address priorities
especially re-supply to patients
Cross-functional dedicated teams with members from both companies will
drive pre-integration process
Manage in full respect to people and values, and ensure regular
communication


Organization for integration
Chris Viehbacher (co-chair)
Belén
Garijo (Integration Leader)
Jérôme
Contamine (Finance)
Karen Linehan (Legal)
Roberto Pucci (HR)
Laure Thibaud (Comm.)
Philippe
Luscan
(IA)
adhoc
Elias Zerhouni (R&D)
adhoc
Sanofi-aventis and Genzyme representation to
be defined by work stream
Integration Project Leader
Henri Termeer
(co-chair)
David Meeker (COO)
Michael S. Wyzga
(Finance)
Tom DesRosier
(Legal)
Zoltan
Csimma
(HR)
Caren Arnstein (Comm.)
Scott Canute (IA)
adhoc
Alan E. Smith (R&D)
adhoc
Integration
Steering Committee
Integration
Coordination
Committee
Work streams


Manufacturing
Proposed high-level organization for integration
HR integration
support & talent
management
Internal/external
communication
Metrics
Process management /
guidelines
Finance
HR
Purchasing
Legal
IT
Real Estate
Quality
work streams (business assessment, strategy, integration model)
Communication
Integration Steering Committee
R&D
3
Operations
Support
Functions
1
2
4
Integration Coordination Committee


High-level calendar
Q1
Q2
Q3
Q4
Legal process
(tender offer,
CVR registration)
Feb
16
th
Merger
agreement
Transaction
closing / Day 1
Understanding
and planning
Business continuity and integration
Feb 16
th
Global Kick-off
pre-integration
Legal
process
Pre-integration
work
Integration
work
Steering
Committees
country level
kick off


Questions & answers