1

Sanofi-aventis

Tender Offer to Acquire

October 4, 2010

Exhibit 99(a)(5)(C)

2

Forward Looking Statements

This presentation contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995,

as amended. Forward-looking statements are statements that are not historical facts.  These statements include

projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions and

expectations with respect to future financial results, events, operations, services, product development and potential, and

statements regarding future performance.  Forward-looking statements are generally identified by the words “expects,”

“anticipates,” “believes,” “intends,” “estimates,” “plans” and similar expressions.  Although sanofi-aventis’ management

believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that

forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to

predict and generally beyond the control of sanofi-aventis, that could cause actual results and developments to differ

materially from those expressed in, or implied or projected by, the forward-looking information and statements.  These

risks and uncertainties include among other things, the uncertainties inherent in research and development, future clinical

data and analysis, including post marketing, decisions by regulatory authorities, such as the FDA or the EMA, regarding

whether and when to approve any drug, device or biological application that may be filed for any such product candidates

as well as their decisions regarding labeling and other matters that could affect the availability or commercial potential of

such products candidates, the absence of guarantee that the products candidates if approved will be commercially

successful, the future approval and commercial success of therapeutic alternatives, the Group’s ability to benefit from

external growth opportunities  as well as those discussed or identified in the public filings with the SEC and the AMF made

by sanofi-aventis, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking

Statements” in sanofi-aventis’ annual report on Form 20-F for the year ended December 31, 2009.  

Other than as required by applicable law, sanofi-aventis does not undertake any obligation to update or revise any

forward-looking information or statements.

Important Additional Information: This communication is neither an offer to purchase nor a solicitation of an offer to sell

any securities. In connection with the proposed transaction, sanofi-aventis and GC Merger Corp. have filed tender offer

documents with the U.S. Securities and Exchange Commission (the “SEC”).  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. The tender offer materials may 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 1-800-322-2885, and may also be obtained at no charge at the website maintained by the

SEC at www.sec.gov.

Sanofi-aventis

Offer Represents Full and Fair Value

for

Genzyme

Acquisition Terms:

All cash offer

of $69.00 per share

Approximately

$18.5 billion purchase

price

38%

premium

over

unaffected

(1)

closing

price

of

$49.86

31%

premium

over

unaffected

(2)

30-day

average

closing

price

of

$52.63

Represents

36x

Genzyme’s

2010E

EPS

and

19x

2011E

EPS

(3)

Financing

already

fully

secured

Offer

scheduled

to

expire

on

December

10

th

3

(1) July

1,

2010;

prior

to

press

speculation

that

sanofi-aventis

was

pursuing

a

large

U.S.

biotech

acquisition

(2) For

period

ending

July

22,

2010;

prior

to

press

speculation

that

sanofi-aventis

made

an

approach

to

acquire

Genzyme

(3) Based on analyst consensus estimates

Sanofi-aventis

Is Commited

to This Transaction

4

Situation Overview:

Multiple attempts to engage with Genzyme

over past few months

Private

offer

letter

sent

on

July

29

th

Genzyme

rejected

offer

on

August

11

th

Financial

advisors

met

briefly

on

August

24

th

Sent

and

publicly

released

second

offer

letter

on

August

29

th

Genzyme

publicly

rejected

offer

on

August

30

th

One

meeting

with

Genzyme

CEO

on

September

20

th

;

no

path

forward

Initiating tender offer today

Creates new platform for 

sustainable growth further

increasing our biotech exposure

Expands footprint in attractive,

growing rare disease market

Increases our U.S. presence and

expands our R&D pipeline of Phase

II and Phase III products

Meets sanofi-aventis value creation

criteria

Preserves strong capital structure

and financial strength

5

Our Compelling Offer is an Attractive Opportunity

for Both Parties

Provides immediate and certain

value for shareholders

Represents a substantial premium

Captures the potential of

Genzyme’s business and pipeline

and shifts execution risk to sanofi-

aventis

Enhances Genzyme’s rare disease

business as a center of excellence

Creates more value for Genzyme’s

other product lines within a larger

company with global reach and

resources

Share

Price Performance since

Company / Index

Jan 1, 2006

Jan 1, 2007

Jan 1, 2008

Jan 1, 2009

Jan 1, 2010

(30%)

(19%)

(33%)

(25%)

2%

S&P 500

(18%)

(28%)

(30%)

14%

(8%)

BTK

47%

33%

27%

55%

6%

6

Genzyme’s

Share Price Has Underperformed Biotech Peers

Source: FactSet

as of 7/1/10

0%

50%

100%

150%

200%

01/03/06

07/27/06

02/17/07

09/10/07

04/02/08

10/24/08

05/17/09

12/08/09

07/01/10

Genzyme

S&P 500

AMEX Biotech Index (BTK)

47%

(18%)

(30%)

7

Our Offer Delivers Significant Value To Genzyme

Shareholders in Excess of Likely Stand-alone Returns

$56.63

$56.39

$53.37

$46.22

$20

$30

$40

$50

$60

$70

$80

2011

2012

2013

2014

Offer price: $69 / share

Assumptions: Mean EPS from I/B/E/S; 13.6x 1-year forward P/E multiple; 10.66% discount rate

Present

Value of Future Stock Price

Source: Factset and IBES estimates, as of October 1, 2010

Note: Implied future share prices based upon Genzyme Mean IBES EPS estimates; 1-year forward Genzyme P/E multiple of 13.6x based on current IBES mean 2011 consensus

estimate of $3.68/share and Genzyme unaffected share price of $49.86 as of July 1, 2010 (July 1, 2010 IBES consensus estimate of $3.79 implied a 13.2x multiple); discounted to

October 1, 2010 based upon 10.66% discount rate per Genzyme Investor Day presentation dated May 6, 2010

8

Our

Offer

Values

Genzyme

Significantly

Higher

than

Peers

despite Near-term Challenges and Recent Underperformance

Source: FactSet

as of 10/1/10

Note: Genzyme

figures based on $69.00 offer and I/B/E/S consensus estimates; net debt excludes unconsolidated assets and minority interests; large biotech peers include

Celgene, Biogen

Idec, Amgen, and Gilead

TEV / 2011E EBITDA

TEV / 2012E EBITDA

2011E P/E

2012E P/E

2011

2012

7.0x

11.6x

0,0x

3,0x

6,0x

9,0x

12,0x

15,0x

Genzyme

@ $69

Large biotech median

18.8x

10.7x

0,0x

5,0x

10,0x

15,0x

20,0x

Genzyme

@ $69

Large biotech median

7.0x

11.1x

0,0x

3,0x

6,0x

9,0x

12,0x

15,0x

Genzyme

@ $69

Large biotech median

10.0x

14.7x

0,0x

5,0x

10,0x

15,0x

20,0x

Genzyme

@

$69

Large biotech median

9

Sanofi-aventis

Offer Premiums are in Line with Large

Biopharmaceutical Transactions

1-day premiums paid

38%

19%

29%

33%

20%

53%

34%

32%

16%

Genzyme at $69

Chiron / Novartis

Schering AG /

Bayer AG

Serono / Merck

KGaA

MedImmune /

AstraZeneca

Alcon / Novartis

Genentech /

Roche

Wyeth / Pfizer

Schering-Plough

/ Merck

Median: 31%

9/1/05

3/23/06

9/21/06

4/23/07

4/8/08

(1)

17.3                      9.4

19.6                        12.1          

15.2                     47.7                        95.8                     65.2                       45.9

Net Deal Value

($bn)

7/21/08

(2)

1-month premiums paid

31%

33%

39%

58%

31%

84%

20%

31%

27%

Genzyme at $69

Chiron /

Novartis

Schering AG /

Bayer AG

Serono / Merck

KGaA

MedImmune /

AstraZeneca

Alcon / Novartis

Genentech /

Roche

Wyeth / Pfizer

Schering-Plough

/ Merck

Median: 32%

9/1/05

3/23/06

9/21/06

4/23/07

4/8/08

(1)

7/21/08

(2)

1/26/09

3/9/09

1/26/09

3/9/09

Source: Public filings, equity research, and FactSet

Note: all premiums are relative to unaffected stock prices; Genzyme 1-day premium based on 7/1/10 and 1-month premium based on 1-month VWAP of $52.63 (as of 7/22/10);

Genzyme net deal value adjusted for announced divestitures

(1) Date Novartis announced purchase of 25% stake and call/put option; blended purchase price of the initial 25% for $10.4bn and remaining 75% at $180/share

(2) Date of initial Roche offer; value grossed up to 100% of Genentech (Roche owned ~55% at time of offer)

14.1x

13.0x

16.9x

18.5x

8.9x

9.4x

27.8x

14.6x

19.2x

Genzyme at

$69

Chiron /

Novartis

Schering AG /

Bayer AG

Serono /

Merck KGaA

Organon /

Schering-

Plough

MedImmune /

AstraZeneca

Alcon /

Novartis

Genentech /

Roche

Wyeth /

Pfizer

Schering-

Plough / Merck

10

Sanofi-aventis Offer Multiples are in Line with Large

Biopharmaceutical Transactions

Transaction value / LTM Revenue

Transaction value / LTM EBITDA

Source: Public filings, equity research, and Factset 

Note: Genzyme net deal value and implied multiples based on 2010E Street consensus estimates adjusted for announced divestitures

(1) Blended purchase price of the initial 25% for $10.4bn and remaining 75% at $180/share

(2) Date of initial Roche offer; value grossed up to 100% of Genentech (Roche owned ~55% at time of offer)

2.5x

2.8x

2.9x

4.6x

3.1x

7.1x

11.2x

4.2x

4.9x

7.3x

Genzyme at

$69

Chiron /

Novartis

Schering AG /

Bayer AG

Serono /

Merck KGaA

Organon /

Schering-

Plough

MedImmune /

AstraZeneca

Alcon /

Novartis

Genentech /

Roche

Wyeth /

Pfizer

Schering-

Plough / Merck

Median: 4.6x

9/1/05

3/23/06

9/21/06

3/12/07

4/23/07

1/4/10

7/21/08

(2)

Median: 14.4x

NM

17.3                     9.4  

19.6                    12.1                  14.4                    15.2                   47.7

(1)

95.8                    65.2                   45.9

Net Deal Value

($bn)

9/1/05

3/23/06

9/21/06

3/12/07

4/23/07

1/4/10

7/21/08

(2)

1/26/09

3/9/09

1/26/09

3/9/09

11

Our

Offer

Assumes

Alemtuzumab

Performs

in

Line

with Analyst Expectations in Multiple Sclerosis

Source: Equity research

(1) Includes all Campath

indications

$1 037

$932

$800

$700

$675

$604

$370

Barclays

Credit Suisse

Deutsche Bank

Bank of America /

Merrill Lynch

Bernstein

Citi

Jefferies

“According to our analysis, alemtuzumab

can reach operating margins of only 28% by 2018.  This is due

to high payments to Bayer, relatively high COGS due to production at a third party, and building a global

sales

force

that

will

be

required

in

Multiple

Sclerosis.”

-

September

17,

2009

“Genzyme

will pay Bayer a 20-35% royalty on sales in Multiple Sclerosis once the drug is approved in

2012.”

-

March 31, 2009

Peak annual sales estimated ($m)

2013                            

2013

2013

2012                               2011                             2013                             2012

Launch year

2020                           

2020

2018                            2015                              2015

2018                              2014

Yr. achieve

peak sales

Median: $700m

(1)

(1)

“While Campath

MS remains one of the more compelling disease modifying therapies for MS, we believe

that

unique

autoimmune

toxicities

and

pricing

challenges

remain

to

be

addressed”

-

June

14,

2010

“We

assume

use

in

Tysabri

failures

at

a

new

patient

add

rate

comparable

to

current

Tysabri

rate

of

200/week”

-

May 7, 2010

Company

Product

Status

Cladribine

(oral)

U.S. filing in June 2010

Negative CHMP opinion

in September 2010

Teriflunomide

(oral)

First Phase III

successfully completed

Alemtuzumab

(IV)

Phase III results

expected in 2011

Dimethyl

Fumarate

(oral)

Phase III results

expected in 2011

Laquinimod

(oral)

Phase III results

expected in 2012

12

Source: Company filings, equity research and EvaluatePharma

(1)

Copaxone

®

is

marketed

outside

the

U.S.

and

Canada

through

our

alliance

with

Teva

(see

our

20-F

filing

for

details

of

our

alliance)

Major MS pipeline drugs ($mm)

$1 692

$1 060

$2 142

$2 323

$2 826

Major approved MS therapies ($m in 2009)

NA

Copaxone

®

Avonex

®

Rebif

®

Betaseron

®

Tysabr

i

®

Gilenya

®

First approved:

1996

(U.S.)

1996

(U.S.)

1997

(EU)

1993

(U.S.)

2004

(U.S.)

2010

(U.S.)

Brand:

Multiple Sclerosis Has Become an Increasingly 

Competitive Market with Gilenya’s Recent Approval

13

Precedent Manufacturing Consent Decrees Took Time

to Resolve

Source: Company filings and equity research

(1) Reflects date of agreement with FDA; Consent Decrees await court approval to become effective

(2) Genzyme

made an initial comment that it expected 2-3 years to complete remediation

Company

Product(s)

Date of consent

decree

(1)

Original

timetable

Date of

resolution

Elapsed time

Fabrazyme

®

,

Cerezyme

®

, Thyrogen

®

24/05/2010

3-4 years to

complete

remediation

(2)

NA

NA

Paxil CR

®

and

Avandamet

®

28/04/2005

NA

06/10/2009

4 years

Multiple products

20/05/2002

3 years

02/08/2007

5 years

Multiple products

03/05/2002

NA

Has not been

lifted to date

>8 years

Diagnostic products

02/11/1999

NA

29/12/2003

4 years

14

Key Reasons Our Offer Is Compelling

Unaffected

Share

Price:

Already

reflected

risks

and

opportunities

Stock aggressively promoted during recent proxy campaign

Plan to divest low-margin assets and buy back stock announced in May

Future

Stock

Expectations:

Lower

than

$69

on

an

“unaffected”

standalone

basis

Analyst one year forward stock price of about $60

Present value of stock based on median estimates through 2014 indicate value of about $56

Premiums

and

Multiples:

In

line

with

other

large

biopharmaceutical

deals

EBITDA multiples of 18.5x 2010E, and 11.6x 2011E

Manufacturing

Issues:

Offer

takes

into

account

recovery

as

well

as

risks

Time, uncertainty, and competitive implications relating to resolution

Other

Valuation

Drivers

Already

Incorporated:

Offer

takes

key

drivers

into

account

Alemtuzumab

in Multiple Sclerosis (risk / reward) and projected cost savings (margin rebound)

Over-diversification:

Non-rare

disease

businesses

lack

the

critical

mass

to

compete

effectively

All

Cash

Offer:

Rewards

Genzyme

shareholders

and

eliminates

risks