UNITED STATES
SECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

---

FORM 10-K

|(Mark One)                                  |                                                                                         
|------------------------------------------- | ----------------------------------------------------------------------------------------
|ý                                           | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934    
|For the fiscal year ended December 31, 2005
|or                                         
|o                                           | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from  to

Commission File No. 0-14680

---

GENZYME CORPORATION(Exact name of registrant as specified in its charter)

|Massachusetts(State or other jurisdiction of
incorporation or organization)         |  | 06-1047163(I.R.S. Employer Identification No.)
|----------------------------------------------------------------------------------- |  | ----------------------------------------------
|500 Kendall Street
Cambridge, Massachusetts(Address of principal executive offices) |  | 02142(Zip Code)                               
|(617) 252-7500
(Registrant's telephone number, including area code)                

Securities registered pursuant to Section 12(b) of the Act: None

Securities registered pursuant to Section 12(g) of the Act: Genzyme Common Stock, $0.01 Par Value ("Genzyme Stock")
Genzyme Stock Purchase Rights

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities
Act. Yes ý    No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the
Act. Yes o    No ý

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past
90 days. Yes ý    No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of
registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of "accelerated filer and large
accelerated filer" in Rule 12b-2 of the Exchange Act. Large accelerated filer ý     Accelerated
filer o    Non-accelerated filer o

Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the Exchange
Act). Yes o    No ý

Aggregate market value of voting stock held by non-affiliates of the Registrant as of June 30, 2005: $15,218,664,105

Number
of shares of Genzyme Stock outstanding as of March 1, 2006: 259,790,498

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Registrant's 2005 Annual Report are incorporated by reference into Parts I, II and IV of this Form 10-K. Portions of the Registrant's Proxy
Statement for the Annual Meeting of Shareholders to be held on May 25, 2006 are incorporated by reference into Part III of this Form 10-K.



---



NOTE REGARDING REFERENCES TO GENZYME DIVISIONS AND SERIES OF STOCK

Throughout
this Form 10-K, the words "we," "us," "our" and "Genzyme" refer to Genzyme Corporation as a whole, and "our board of directors" refers to the board of directors of
Genzyme Corporation.

Through
June 30, 2003, we had three operating divisions, which we refer to as follows:



Through
June 30, 2003, we also had three outstanding series of common stock. Each series was designed to reflect the value and track the performance of one of our divisions. We
refer to each series of common stock as follows:



Through
June 30, 2003, we allocated earnings or losses to each series of tracking stock based on the net income or loss attributable to the corresponding division determined in
accordance with accounting principles generally accepted in the United States of America, as adjusted for the allocation of tax benefits.

Effective
July 1, 2003, we eliminated our tracking stock capital structure by exchanging, in accordance with the provisions of our charter, each share of Biosurgery Stock for
0.04914 of a share of Genzyme General Stock and each share of Molecular Oncology Stock for 0.05653 of a share of Genzyme General Stock. Options and warrants to purchase shares of Biosurgery Stock and
options to purchase shares of Molecular Oncology Stock were converted into options and warrants to purchase shares of Genzyme General Stock. Effective July 1, 2003, we have one outstanding
series of common stock. From July 1, 2003 through May 27, 2004, we referred to our outstanding series of common stock as Genzyme General Stock. At our annual meeting of shareholders on
May 27, 2004, our shareholders approved an amendment to our charter that eliminated the designation of separate series of common stock, resulting in 690,000,000 authorized shares of a single
series of common stock, which we now refer to as Genzyme Stock, and 10,000,000 authorized shares of preferred stock, of which 3,000,000 are designated Series A Junior Participating Preferred
Stock and 7,000,000 are undesignated.

Effective
July 1, 2003, as a result of the elimination of our tracking stock capital structure, all of our earnings or losses are now allocated to Genzyme Stock. Earnings or
losses allocated to Biosurgery Stock and Molecular Oncology Stock prior to that date remain allocated to those series of stock in the preparation of our consolidated financial statements and are not
affected by the elimination of our tracking stock structure. Accordingly, earnings or losses allocated to Biosurgery Stock and Molecular Oncology Stock represent earnings allocated to those tracking
stocks through June 30, 2003. Earnings or losses allocated to Genzyme Stock through June 30, 2003 represent the earnings or losses of Genzyme General, as adjusted for the allocation of
tax benefits. Earnings or losses allocated to Genzyme Stock after June 30, 2003 represent the earnings or losses for the corporation as a whole.

On
July 1, 2003, we reclassified the Biosurgery Stock and Molecular Oncology Stock equity accounts into the Genzyme Stock equity accounts. The elimination of our tracking stock
capital structure had no effect on our consolidated net income or loss. Because we now have only one series of common stock outstanding, we rescinded the management and accounting policies that
governed the relationships between our former divisions. In this Annual Report on Form 10-K, and future Quarterly

2

---



and
Annual Reports, we will not provide separate financial statements and management's discussion and analysis for each of our former divisions, but will continue to provide our consolidated financial
statements and management's discussion and analysis for the corporation as a whole.

NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Form 10-K contains forward-looking statements, including statements regarding:



3

---





These
statements are subject to risks and uncertainties, and our actual results may differ materially from those that are described in this report. These risks and uncertainties include:



4

---





We
have included more detailed descriptions of these and other risks and uncertainties in Item 1A. of this report under the heading "Risk Factors." We encourage you to read those
descriptions carefully. We caution investors not to place substantial reliance on the forward-looking statements contained in this report. These statements, like all statements in this report, speak
only as of the date of this report (unless another date is indicated) and we undertake no obligation to update or revise the statements.

NOTE REGARDING INCORPORATION BY REFERENCE

The Securities and Exchange Commission, commonly referred to as the SEC, allows us to disclose important information to you by referring you to other documents we
have filed or will file with the SEC. The information that we refer you to is "incorporated by reference" into this Form 10-K. Please read that information.

NOTE REGARDING TRADEMARKS

Genzyme®, Cerezyme®, Ceredase®, Fabrazyme®, Thyrogen®, Aldurazyme®, Myozyme®,
Renagel®, Thymoglobulin®, Campath®, Clolar®, Synvisc®, Carticel®, MACI®, Seprafilm®,
Hylaform®, Hectorol® and IMPATH® are registered trademarks, and VERIGEN, Lymphoglobuline and Sepra are trademarks of Genzyme
or its subsidiaries. WelChol® is a registered trademark of Sankyo Pharma, Inc. Gengraf® is a registered trademark of Abbott Laboratories. All rights reserved.

5

---





TABLE OF CONTENTS

|         |  |                                                                                                              |  | PAGE
|-------- |  | ------------------------------------------------------------------------------------------------------------ |  | ----
|PART I   |  |                                                                                                             
|ITEM 1.  |  | BUSINESS                                                                                                     |  | 7   
|         |  | Introduction                                                                                                 |  | 7   
|         |  | Products and Development Programs                                                                            |  | 7   
|         |  | Competition                                                                                                  |  | 12  
|         |  | Patents, License Agreements and Trademarks                                                                   |  | 16  
|         |  | Government Regulation                                                                                        |  | 17  
|         |  | Employees                                                                                                    |  | 22  
|         |  | Financial Information Regarding Segment Reporting                                                            |  | 22  
|         |  | Research and Development Costs                                                                               |  | 22  
|         |  | Sales by Geographic Area, Significant Customers and Products                                                 |  | 22  
|         |  | Available Information                                                                                        |  | 22  
|ITEM 1A. |  | RISK FACTORS                                                                                                 |  | 22  
|ITEM 1B. |  | UNRESOLVED STAFF COMMENTS                                                                                    |  | 23  
|ITEM 2.  |  | PROPERTIES                                                                                                   |  | 23  
|ITEM 3.  |  | LEGAL PROCEEDINGS                                                                                            |  | 24  
|ITEM 4.  |  | SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS                                                          |  | 25  
|         |  | EXECUTIVE OFFICERS OF THE REGISTRANT                                                                         |  | 25  
|PART II  |  |                                                                                                             
|ITEM 5.  |  | MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES |  | 28  
|ITEM 6.  |  | SELECTED FINANCIAL DATA                                                                                      |  | 28  
|ITEM 7.  |  | MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS                        |  | 29  
|ITEM 7A. |  | QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK                                                   |  | 29  
|ITEM 8.  |  | FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA                                                                  |  | 29  
|ITEM 9.  |  | CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE                         |  | 29  
|ITEM 9A. |  | CONTROLS AND PROCEDURES                                                                                      |  | 29  
|ITEM 9B. |  | OTHER INFORMATION                                                                                            |  | 29  
|PART III |  |                                                                                                             
|ITEM 10. |  | DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT                                                           |  | 30  
|ITEM 11. |  | EXECUTIVE COMPENSATION                                                                                       |  | 30  
|ITEM 12. |  | SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS               |  | 30  
|ITEM 13. |  | CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS                                                               |  | 30  
|ITEM 14. |  | PRINCIPAL ACCOUNTING FEES AND SERVICES                                                                       |  | 30  
|PART IV  |  |                                                                                                             
|ITEM 15. |  | EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K                                              |  | 31  
|         |  | 15(a)(1) Financial Statements                                                                                |  | 31  
|         |  | 15(a)(2) Financial Statement Schedules                                                                       |  | 32  
|         |  | 15(a)(3) Exhibits                                                                                            |  | 32  
|         |  | 15(b) Exhibits                                                                                               |  | 32  

6

---





PART I

ITEM 1.    BUSINESS

Introduction

We are a global biotechnology company dedicated to making a major impact on the lives of people with serious diseases. Our broad product and service portfolio is
focused on rare disorders, renal disease, orthopaedics, organ transplant, and diagnostic and predictive testing. We are organized into five financial reporting units, which we also consider to be our
reporting segments:



We
report the activities of our oncology, bulk pharmaceuticals, including sales of WelChol, and cardiovascular business units under the caption "Other."

We
have reclassified our 2004 and 2003 segment disclosures to conform to our 2005 presentation.

Products and Development Programs

Renal

Renagel (sevelamer hydrochloride).Renagel is a non-absorbed, calcium-free, metal-free phosphate binder indicated for the control of serum
phosphorus in patients with chronic kidney disease (CKD) on hemodialysis. Three formulations of the product have been approved for sale in the United Statesthe 403 mg. capsules were
launched in the fourth quarter of 1998, and the 400 and 800 mg. tablets were launched in September 2000. We ceased marketing the 403 mg. capsules in 2004. Renagel was approved for sale in
Israel in 1999, the European Union and Canada in 2000, Brazil in 2002, Japan in 2003, and Argentina and Australia in 2005. In the United States, there are an estimated 350,000 end-stage renal disease
patients, approximately 95% of whom receive a phosphate control product. There are also an estimated 324,000 end-stage renal disease patients in Europe, 60,000 in Brazil, 20,000 in Canada and 200,000
in Japan. We are now marketing the product in a total of 50 countries. In 2005, we received marketing approval in Argentina, Australia, Lebanon and Saudi Arabia and we filed for marketing approval in
Peru and Mexico.

7

---



We
market Renagel tablets in the United States, the European Union and Brazil directly to nephrologists through a dedicated sales force. In the United States, approximately
80%85% of our Renagel sales are made to three large wholesalers. These wholesalers distribute Renagel to retail pharmacies, hospitals and other providers of medication to patients. Chugai
Pharmaceutical Co., Ltd. and its partner, Kirin Brewery Co., Ltd., have rights to develop and market Renagel in Japan, China and other Pacific Rim countries. Our sales of Renagel
(including sales of bulk sevelamer), totaled $417.5 million or 17% of our consolidated product revenues in 2005, $363.7 million, or 18% of our consolidated product revenues in 2004, and
$281.7 million, or 18% of our consolidated product revenues, in 2003.

In
October 2003, the National Kidney Foundation (NKF) published clinical practice guidelines related to bone metabolism and disease in patients with CKD. These guidelines, which
are part of the NKF's Kidney Disease Outcomes Quality Initiative (K/DOQI), include Renagel among first-line options for reducing phosphorus in hemodialysis. Elevated phosphorus levels are associated
with increased morbidity and mortality. The guidelines also define a broader set of patients for whom calcium-based phosphate binders are not appropriate. Renagel is the only marketed phosphate binder
available to patients on hemodialysis that does not contain either calcium or metal, is not absorbed systemically and does not accumulate in the body.

We
conducted a 2,100-patient post-marketing study of Renagel to evaluate the ability of the product to improve patient morbidity and mortality. The Dialysis Clinical Outcomes Revisited
(DCOR) trial compared Renagel to calcium-based phosphate binders with respect to overall morbidity and mortality. We released top-line data from this trial in July 2005 and presented the data
at the American Society of Nephrology meeting in November 2005. The study did not meet its primary end point of a statistically significant reduction in all cause mortality. However, in a
pre-specified sub-group analysis, Renagel demonstrated a significant reduction in all cause mortality in patients 65 years of age or older and in patients using Renagel for two years or more.
We expect to receive morbidity data from the Centers for Medicare and Medicaid Services (CMS) in mid 2006 and may present such data later in the year.

We
currently have two on-going clinical trials for sevelamer carbonate. We completed enrollment in the trial of this therapy in hemodialysis patients in 2005, while the trial in those
with CKD not yet on dialysis began in January 2006. In addition, we are developing a powder formulation of sevelamer carbonate, and in 2005 began a clinical trial comparing it to the tablet
formulation for patients with end-stage renal disease on dialysis. We expect this formulation to allow us access to patients who have trouble swallowing tablets. In 2006, we plan to begin a trial with
the powder formulation to allow once daily dosing of sevelamer carbonate.

Hectorol (doxercalciferol).We added Hectorol to our product portfolio in July 2005 with our acquisition of Bone Care. Hectorol is a line
of vitamin D2 pro-hormone products that are indicated for the treatment of secondary hyperparathyroidism in patients with stages 3 and 4 CKD (0.5 mcg capsules) and in patients with stage 5
CKD on dialysis (2.5 mcg capsules and injection). Hectorol provides significant parathyroid hormone (PTH) reductions with minimal impact on calcium and phosphorus levels. Three formulations of the
product have been approved for commercial sale in the United Statesthe 2.5 mcg capsules were approved in 1999, the 0.5 mcg capsules were approved in 2004 and the intravenous formulation
was approved in 2000. The 2.5 mcg formulation also is approved in Canada, where it is marketed and sold by Shire BioChem, a Canadian subsidiary of Shire plc.

We
market Hectorol in the United States through a direct sales force focused on nephrologists. Approximately 85%90% of our United States Hectorol capsule sales are made to
three large wholesalers, who then sell and distribute the product to retail pharmacies, hospitals and other providers of medication to patients. For Hectorol IV, approximately 80%85% of
our sales are made to three primary wholesalers who then sell and distribute the product to dialysis chains and hospitals. We

8

---



estimate
that there are more than 2.5 million patients in the United States with stage 3 and stage 4 CKD who have elevated PTH levels, although only a much smaller number of
patients are being treated for the condition.

Therapeutics

Our Therapeutics segment currently has four therapeutic products on the market and several other therapeutic products in varying stages of development. The chart
set forth below provides summary information on these four products and our most advanced product candidate as of March 1, 2006.

|Product           |  | Indication                                                                                       |  | Status                                                                                                                                                                                                                                                                                                                                          
|----------------- |  | ------------------------------------------------------------------------------------------------ |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Cerezyme/Ceredase |  | Type 1 Gaucher disease;
Type 3 Gaucher disease
(Cerezyme/E.U. only)                              |  | Ceredase sold commercially since 1991; Cerezyme marketed since 1994; marketing approval received and commercial sales in 51 countries                                                                                                                                                                                                           
|Fabrazyme         |  | Fabry disease                                                                                    |  | Marketed in the E.U. since 2001, the U.S. since 2003, and Japan since 2004; marketing approval received in 44 countries and commercial sales in 31 countries; several post-marketing commitments ongoing                                                                                                                                        
|Thyrogen          |  | Adjunctive diagnostic agent in the follow-up of patients with well-differentiated thyroid cancer |  | Marketed in the U.S. since 1998, Brazil since 2000 and the E.U. since 2001; marketing approval received and commercial sales in 42 countries                                                                                                                                                                                                    
|                  |  | Combination therapy in ablation of remnant thyroid tissue                                        |  | Marketing approval received in the E.U. in March 2005                                                                                                                                                                                                                                                                                           
|Aldurazyme        |  | MPS I                                                                                            |  | Marketed in the U.S. and the E.U. since 2003; marketing approval received in 37 countries and commercial sales in 30 countries; several post-marketing commitments on-going                                                                                                                                                                     
|Myozyme           |  | Pompe disease                                                                                    |  | Two phase 3 trials in patients younger than 3 years old completed; submitted MAA for marketing approval in E.U. in late 2004 and Biologic License Application (BLA) for marketing approval in U.S. in mid-2005; initiated a pivotal study in late onset
disease in 2005; expect commercial launch in U.S. and E.U. in the second quarter of 2006

Additional details on our Therapeutic products and our largest development program are set forth below.

Cerezyme (imiglucerase).Treatment with Cerezyme enzyme replacement therapy currently represents the only safe and effective enzyme
replacement therapy approved for treatment of Type 1 Gaucher disease,
an LSD. In the E.U., Cerezyme is also approved for the treatment of patients who exhibit clinically significant, non-neurological manifestations of the disease (Type 3 Gaucher disease).

We
market Cerezyme directly to physicians, hospitals and treatment centers worldwide through a highly specialized sales force. Cerezyme, like all of our therapies developed for LSDs, is
aimed at treating a patient population of less than 10,000 worldwide. Cerezyme has received marketing approval and we are selling Cerezyme in 51 countries to treat symptoms that include anemia,
spleen and liver enlargement and bone deterioration. Our results of operations are highly dependent on sales of this product, although our dependence is lessening as we diversify our product
portfolio. Sales of Cerezyme

9

---



totaled
$932.3 million, or 38% of our consolidated product revenues in 2005, $839.4 million, or 42% of our consolidated product revenues in 2004, and $733.8 million, or 47% of our
consolidated product revenues in 2003.

Fabrazyme (agalsidase beta).We have developed Fabrazyme, a recombinant form of the human enzyme alpha-galactosidase, as a treatment for
Fabry disease. Fabry disease is an LSD that is caused by a deficiency of the enzyme alpha-galactosidase A, which leads to the progressive accumulation of lipids within cells of the kidneys, heart and
other organs. It is estimated to affect fewer than 10,000 people worldwide. Fabrazyme received marketing approval in the European Union in 2001, in the United States in 2003 and in Japan in 2004. In
agreement with the FDA, we undertook a number of post-marketing commitments, and have completed a phase 4, multi-national, multi-center, double-blind placebo-controlled study. In mid-2005, the EMEA
approved new labeling for Fabrazyme based largely on the results from the phase 4 study. In total, Fabrazyme has received marketing approval in 44 countries and we are selling Fabrazyme commercially
in 31 countries. Because kidney failure is associated with Fabry disease, Fabrazyme is sold by our existing LSD and Renal sales forces.

Thyrogen (thyrotropin alfa).Thyrogen is an adjunctive diagnostic agent used in the follow-up of patients with well-differentiated thyroid
cancer. We developed this product to allow patients to continue taking their thyroid hormone supplements while they are being screened for residual or recurring thyroid cancer. This helps patients
avoid the debilitating effects of hypothyroidism, increasing the likelihood that they will seek follow-up treatment, and ultimately improve the likelihood of early detection of any recurrent disease.
We began marketing Thyrogen in the United States in 1998, in Brazil in 2000 and in the European Union in 2001. In the United States and the European Union, physicians order over 200,000 thyroid cancer
screening tests per year. Thyrogen, which has received marketing approval and is being sold commercially in 42 countries, is promoted by a dedicated sales force, and sold through distributors in the
United States, Brazil and the European Union.

We
currently are pursuing additional indications for Thyrogen. In March 2005, we received European Union approval for use of Thyrogen in combination with radioiodine in ablation
of thyroid tissue. We have received an approvable letter for this indication from the FDA and expect approval in the United States, Brazil and Canada in late 2006. Approximately 35,000 ablation
procedures are performed
annually in the United States and European Union combined, and we believe that Thyrogen has the potential to be used in up to 80% of these procedures. We are also in the process of commencing a phase
2 trial of TSH, the active ingredient in Thyrogen, for use in patients with nontoxic multinodular goiter.

Aldurazyme (laronidase).We formed a joint venture with BioMarin Pharmaceutical Inc., or BioMarin, to develop and market Aldurazyme,
a recombinant form of the human enzyme alpha-L-iduronidase, to treat a LSD known as mucopolysaccharidosis I, or MPS I. MPS I is a progressive, debilitating, and often life-threatening disease that
affects fewer than 10,000 people worldwide. The disease encompasses a wide and continuous spectrum of clinical presentations, historically classified as "Hurler," "Hurler-Scheie" and "Scheie"
syndromes. In 2003, the joint venture received marketing approval for Aldurazyme in both the United States and the European Union. We market Aldurazyme directly to physicians in the United States
through our LSD sales force. European sales of Aldurazyme, which are undertaken by our European sales and marketing teams, are being realized on a country-by-country basis as pricing and reimbursement
approvals are obtained. The joint venture's applications for marketing approval are currently pending in several countries, including Japan, Australia and several countries in Central and Eastern
Europe, as well as the Asia-Pacific rim. In total, Aldurazyme has received marketing approvals in 37 countries and we are selling Aldurazyme commercially, on behalf of the joint venture, in 30
countries. We currently are conducting a clinical study to support our marketing application in Japan, which we expect to complete in 2006. We are also conducting a post-marketing clinical study
investigating alternative dosing regimens that we anticipate completing in 2006.

10

---



Aldurazyme
revenues are recorded by the joint venture. We include our portion of the net income of BioMarin/Genzyme LLC in equity in income (loss) of equity method investments in our consolidated
statements of operations.

Myozyme (alglucosidase alfa).We are developing Myozyme as a therapy for Pompe disease, a progressive and often fatal muscle disease
resulting from an inherited enzyme deficiency. Pompe disease ranges from a rapidly fatal infantile-onset form with severe cardiac and skeletal muscle involvement to a more slowly progressive
late-onset form affecting skeletal and respiratory muscle. There is currently no therapeutic treatment available for the disease. Based on results from two trials involving patients younger than
3 years old with the infantile-onset form of Pompe disease, and from previous studies of enzyme replacement therapy for Pompe disease, we submitted a marketing application for Myozyme in the
European Union in late 2004 and in the United States in mid-2005. In January 2006, European regulators issued a positive opinion on Myozyme. We expect European Union and United States approvals
in the second quarter of 2006 and are preparing for commercial launch soon thereafter. We plan to submit a marketing application in Japan later in 2006. In addition, we are continuing enrollment in
the clinical trials of Myozyme in patients with the late-onset form of Pompe disease that began in 2005. Myozyme currently is available to patients who are in need and are unable to participate in our
trials through several special access programs.

Transplant

This business segment includes three marketed products, as well as product candidates in the research and development stages that we acquired through our
acquisition of SangStat in the third quarter of 2003. Set forth below is a discussion of the two marketed products that are the primary revenue drivers for the Transplant segment.

Thymoglobulin (anti-thymocyte globulin, rabbit).Thymoglobulin is an immunosuppressive polyclonal antibody that suppresses certain types of
immune cells responsible for acute organ rejection in transplant patients. It has been marketed in the United States since 1999 for the treatment, and in Canada since 2003 for the prevention and
treatment, of acute rejection in patients with renal transplant. More kidney transplants are performed in the United States than any other organ transplant, with approximately 16,000 transplants
performed each year. Of this number of renal transplants, we estimate that acute immunosuppressant therapies such as Thymoglobulin are used in approximately 75% of procedures. In the European Union,
Thymoglobulin received approval for a broader label in the major European markets and is indicated for induction and treatment of rejection in solid organ transplants, for prevention and treatment of
graft versus host disease, and for the treatment of aplastic anemia. This broader indication is also held in several Asian and Latin American countries. We have filed for marketing approval of
Thymoglobulin in Japan. Thymoglobulin, which is commercially available in 55 countries, is sold through a direct sales force or through distributors to transplant centers for end use by transplant
surgeons and nephrologists. In 2005, we completed enrollment in a phase 2 trial of Thymoglobulin to prevent rejection of transplanted kidneys from living organ donors and began a phase 2 trial in
liver transplantation. We closed our trial of Thymoglobulin as a conditioning therapy for bone marrow transplant in cases of severe leukemia in order to devote our efforts to other aspects of
hematological cancers.

Lymphoglobuline (anti-thymocyte-globuline, equine).We market Lymphoglobuline, another immunosuppressive polyclonal antibody, in Latin
America, the European Union, and certain Asia Pacific countries for the treatment of aplastic anemia and for the prevention and treatment of graft rejection. This product is sold through our sales
force in Europe and through distributors elsewhere.

11

---



Biosurgery

Synvisc (hylan G-F 20).Synvisc is a biomaterial derived from hyaluronan used to treat the pain associated with osteoarthritis of the knee.
An estimated 8 to 9 million of the approximately 14 million people in the United States with osteoarthritis of the knee may be candidates for treatment with Synvisc. Synvisc is sold
commercially in over 60 countries, both directly and through marketing and distribution arrangements. At the beginning of 2005, we re-acquired from Wyeth the sales and marketing rights to the product
in the United States and several European countries.

We
are investing in research and clinical trials to expand the use of Synvisc to additional joints and through next-generation approaches. We have completed enrollment in a phase 3
clinical trial in the United States for Synvisc in the hip, an indication that is already approved in the European Union and Canada. We anticipate filing for approval of this indication in the United
States in late 2006. In the European Union, we have completed our phase 3 trials of the shoulder and ankle and anticipate launching Synvisc for these indications in the first half of 2007. At the same
time, we are continuing clinical development of Synvisc II, our next-generation product that would require fewer injections. We hope to launch this product in 2007.

Sepra Products.The Sepra family of products is aimed primarily at preventing adhesions (internal scar tissue) following various surgical
procedures in areas of the body such as the abdomen and pelvis. These products are biomaterials derived from hyaluronan. We market the Sepra products primarily through a direct sales force in the
United States and France, and primarily through distribution arrangements in Japan and the rest of the world.

Seprafilm,
the first marketed product and largest by sales volume of the Sepra family, is the only FDA-approved product clinically proven to reduce the incidence, extent and severity of
postsurgical adhesions in both the abdomen and pelvis. There are approximately 2 million applicable abdominal and pelvic procedures performed annually in the United States, including
1.1 million Cesarean sections, a largely untapped market. During 2005, we launched Sepramesh IP, a second generation product for hernia repair to replace Sepramesh, which has been on the market
since 2000.

Diagnostics/Genetics

Diagnostic Products.We develop, market and distributein vitrodiagnostic products with an
emphasis on point of care products for the in-hospital and out-of-hospital rapid test segment, and clinical chemistry reagents and raw materials focused on the clinical laboratory. Sales in Europe and
the United States are made primarily to diagnostic reagent and equipment manufacturers who, in turn, distribute the products under their own brand. In Japan, sales are primarily made to distributors.
We also maintain a manufacturing, research and development and sales subsidiary in Germany that sells infectious disease diagnostic products directly to hospital laboratories.

Diagnostic Services.We develop and provide high quality, sophisticated and complex testing, and offer genetic counseling services focused
on pre-natal and post-natal care, reproductive and fertility medicine, and oncology in both the United States and Japan. We offer several types of testingthe most significant are
cytogenetic testing, molecular genetic (DNA) testing, immunohistochemistry testing, flow cytometry testing and biochemical testing. These services are promoted through a direct sales force in the
United States, with testing performed in our nine clinical laboratories located throughout the United States. We service the Japanese market through a direct sales force and distributors, with testing
primarily performed in our clinical laboratory in Santa Fe, New Mexico.

Competition

We are engaged in segments of the human healthcare products and services industry that are extremely competitive. Our competitors in the United States and
elsewhere include major

12

---



pharmaceutical,
biotechnology, diagnostic testing and medical device companies. Some of these competitors may have more extensive research and development, regulatory, manufacturing, production, and
sales and marketing capabilities. Some competitors may have greater financial resources. These companies may succeed in developing products and services that are more effective than any that we have
or may develop and may also prove to be more successful than we are in producing, marketing and selling products and services. In addition, technological advances or different approaches developed by
one or more of our competitors may render our products and services obsolete, less effective or uneconomical. Each of our products and services faces different competitive challenges, and we describe
many of them below.

Renal

Renagel is a phosphate binder for the treatment of hyperphosphatemia. Phosphate binders, such as Renagel, are currently the only available treatment for
hyperphosphatemia, or elevated serum phosphorus levels. There are several phosphate binders available or under development. PhosLo®, a prescription calcium acetate preparation sold by Nabi
Biopharmaceuticals, and Fosrenol®, a prescription lanthanum carbonate sold by Shire plc, or Shire, are the only other products approved in the United States for the control of elevated
phosphorus levels in patients with chronic kidney failure and on hemodialysis. Other products used as phosphate binders include over-the-counter calcium- and aluminum-based antacids and dietary
calcium supplements. The doses necessary for calcium acetate and calcium carbonate, the most commonly used agents, to achieve adequate reductions in phosphate absorption can lead to constipation and
patient noncompliance. In addition, calcium therapy requires frequent monitoring because its use can cause hypercalcemia and evidence suggests that increasing doses of calcium-based binders may lead
to cardiac calcification. Aluminum hydroxide, another treatment option, is more effective at lower doses than calcium acetate
or calcium carbonate, but it is infrequently used because aluminum absorbed from the intestinal tract accumulates in the tissues of patients with chronic kidney failure, causing aluminum-related
osteomalacia, anemia and dementia. We are aware of several potential treatments under development for hyperphosphatemia in end-stage renal disease. In addition, current competitors are looking to
expand into new markets. Shire has received marketing approval of Fosrenol in certain European countries and Australia, and has filed for approval in additional European countries and Canada. Nabi
Biopharmaceuticals has filed for marketing approval for PhosLo in the European Union.

Hectorol.Dialysis providers typically select which therapy a CKD patient receives to treat secondary hyperparathyroidism based on safety,
efficacy and cost. Abbott Laboratories, Inc., or Abbott, markets intravenous calcitriol (brand name Calcijex®) and intravenous paricalcitol (brand name Zemplar®) for
end-stage renal disease patients. Current intravenous versions of these drugs are approved to manage secondary hyperparathyroidism in end-stage renal disease patients in the United States and in
European countries. A number of companies have launched or are planning to launch generic intravenous calcitriol in the United States. In 2005, Abbott received approval to market oral paricalcitol
(Zemplar) in the United States for patients with stages 3 and 4 CKD. Since 2004, Amgen, Inc. has been marketing in the United States an oral calcimimetic agent for the treatment of secondary
hyperparathyroidism in patients with CKD on dialysis. The majority of patients studied on this calcimimetic agent were also taking vitamin D hormone to treat secondary hyperparathyroidism. Roche
Pharmaceuticals markets oral calcitriol (brand name Rocaltrol®) and Teva Pharmaceuticals, or Teva, markets generic oral calcitriol in the United States to manage secondary
hyperparathyroidism in CKD patients. These two products are approved in the United States for the treatment of elevated parathyroid hormone in both end-stage renal disease and pre-dialysis CKD.

13

---



Therapeutics

Cerezyme.There is one marketed product aimed at treating Gaucher disease, as well as on-going development efforts. Zavesca®, a
small molecule oral therapy developed by CellTech Group plc, which was acquired by UCB S.A. in 2004, and marketed by Teva in Israel and Actelion Ltd. in the United States and the European
Union, has been approved for use in patients with mild to moderate Type 1 Gaucher disease for whom enzyme replacement therapy is unsuitable. To date, virtually all Gaucher disease patients who have
received enzyme therapy have experienced strong clinical benefits with few side effects, so we do not expect the competition from Zavesca to have a significant impact on our sales of Cerezyme. Shire
is conducting a phase 1/2 clinical trial for its gene-activated human glucocerebrosidase (GA-GCB) product. Shire did not report top-line data from this study in 2005 as expected. In addition, in
November 2005, Protalix announced they had begun recruitment for a phase 1 trial with their human glucocerebrosidase (prGCB) therapy expressed and purified in a bioreactor system from
transformed carrot cells. Amicus Therapeutics also has announced plans to begin a phase 1 trial using an experimental pharmacological chaperone (AT-2101) in the first
half of 2006. Other competitors could develop competitive products based on protein replacement therapy, small molecule or gene therapy approaches.

Fabrazyme.Fabrazyme has marketing exclusivity in the United States until 2010 due to its orphan drug status. Replagal®,
Shire's enzyme replacement therapy for Fabry disease, competes with Fabrazyme in the European Union, Australia, Canada, Iceland, Israel, New Zealand, Norway, Romania, Switzerland and Taiwan.
Transkaryotic Therapies, Inc., prior to its acquisition by Shire, publicly announced that it had abandoned its efforts to obtain marketing approval in the United States. In addition, Amicus
Therapeutics is conducting a phase 2 study of a small molecule treatment for Fabry disease.

Aldurazyme.Aldurazyme has marketing exclusivity in the United States until 2010 and in the European Union until 2013 due to its orphan
drug status.

Transplant

Thymoglobulin and Lymphoglobuline.Several companies market products used for the prevention and treatment of acute rejection in renal
transplant. These products include Novartis AG's Simulect®, Pfizer Inc.'s ATGAM®, Ortho Biotech's Orthoclone OKT®3, Fresenius Biotech GmbH's
ATG-Fresenius S® and the Roche Group's Zenapax®. Competition in the acute transplant rejection market largely is driven by product efficacy due to the potential loss of
transplanted organs as the result of an acute organ rejection episode.

Biosurgery

Synvisc.Current competition for Synvisc includes Supartz®, a product manufactured by Seikagaku Kogyo that is sold in the
United States by Smith & Nephew Orthopaedics and in Japan by Kaken Pharmaceutical Co. under the name Artz®; Hyalgan®, produced by Fidia S.p.A. and marketed in the United
States by Sanofi-Aventis; Orthovisc®, produced by Anika Therapeutics, Inc., marketed in the United States by Johnson & Johnson and marketed outside the United States through
distributors; Euflexxa, a product manufactured and sold by Ferring Pharmaceuticals in the United States and Europe; and Durolane®, manufactured and marketed outside the United
States by Q-Med AB. Durolane and Euflexxa, the most recently approved products in Europe and the United States, respectively, are produced by bacterial fermentation, as opposed to Synvisc, which is
avian-sourced. In addition, the treatment protocol for Durolane is a single injection, as compared to Synvisc's three injection regimen (although it offers a shorter duration of pain relief).
Production via bacterial fermentation and treatment with a reduced number of injections may represent competitive advantages for these products. We are aware of various viscosupplementation products
on the market or in

14

---



development,
but are unaware of any products that have physical properties of viscosity, elasticity or molecular weight comparable to those of Synvisc.

Sepra Products.The Sepra products face competition from other adhesion prevention technologies. Another competitive factor is acceptance
of the product by surgeons and the performance by surgeons of procedures for which the product is indicated, which, in each case, depends not only upon product efficacy and safety, but also on proven
clinical outcomes.

Seprafilm
does not have significant direct competition in the area of abdominal surgery in the United States, but does compete with other products in other indications. Outside the
United States, Seprafilm competes with several adhesion prevention products. Gynecare markets Interceed®, an adhesion barrier that has properties similar to Seprafilm, but is indicated
only for selected gynecological indications. Innovata plc's Adept® solution is approved in the European Union for abdominal and gynecological surgeries. Innovata has filed for approval of
Adept in the United States and recently announced a global distribution agreement with Baxter. FzioMed, Inc. has received CE Mark approval in the European Union for Oxiplex®/AP Gel,
an adhesion barrier for abdominal/pelvic surgery and is conducting a pivotal clinical trial in the United States. Life Medical Sciences, Inc. is developing several adhesion prevention products,
including REPEL for gynecologic surgery and REPEL-CV for cardiovascular surgery. Confluent Surgical, Inc.'s Spraygel, an adhesion barrier used in
abdominopelvic procedures, is approved for sale in certain European countries. MAST Biosurgery AG's bioresorbable film product, SurgiWrap, is CE marked with an indication for abdominal
and pelvic adhesion prevention, but holds an FDA clearance as a surgical mesh in the United States. In addition, FzioMed's Oxiplex®/SP Gel, an adhesion barrier for spine surgery, is
approved for sale in the European Union and in other countries outside the United States.

Diagnostics/Genetics

Diagnostic Products.For enzymes and substrates, our primary competitors are Roche Diagnostics, Amano Enzyme Europe Ltd.,
Toyobo, Ltd. and OYC International, Inc. Our complete diagnostic kits are available to any main frame analyzer chemistry company for OEM use. We do not generally compete with those
customers in the sale of finished reagents. The market in the diagnostic products industry is mature and competition is based on service, quality, technical support, price, and reliability and
consistency of supply. In the rapid test arena at the point of care, there are several competitors, among them Acon Laboratories, Inc., Inverness Medical Innovations, Inc., Becton
Dickinson & Co., Beckman Coulter, Inc. and Quidel Corp. Market success is largely dependent on product performance, sales and technical support, breadth of menu and price.

Diagnostic Services.The United States market for genetic and complex testing is highly competitive and is divided among many laboratories,
the largest of which are Quest Diagnostics and LabCorp. In addition, many hospitals provide some or all of these services through in-house laboratories. Competitive factors in the genetic and complex
testing and diagnostic services business generally include reputation of the laboratory, range of services offered, pricing, managed care contracts, convenience of sample collection and pick-up,
quality of analysis and reporting, timeliness of delivery of completed reports and levels of automation and information technology solutions.

15

---



Patents, License Agreements and Trademarks

In general, we pursue a policy of obtaining patent protection both in the United States and in selected countries outside the United States for subject matter we
consider patentable and important to our business. Patents owned by us that we consider material include the following:

Renal

Renagel is protected by U.S. Patent Nos. 5,667,775, which expires on September 16, 2014; 5,496,545 and 6,509,013 which expire August 11,
2013; 6,733,780, which expires on October 18, 2020; and corresponding international counterparts. Hectorol is protected by U.S. Patent Nos. 6,903,383 which expires on July 18,
2021; 5,602,116 which expires on February 11, 2014; 5,707,980 which expires on August 17, 2010; 5,869,473 which expires on August 2, 2008; 5,869,472 which expires on
July 18, 2014, and corresponding international counterparts.

Therapeutics

Cerezyme is protected by U.S. Patent Nos. 5,236,838 which expires August 17, 2010; 5,549,892 which expires August 27, 2013; 6,451,600 which expires
September 17, 2019; and corresponding international counterparts. Myozyme is protected by U.S. Patent No. 6,118,045 which expires July 31, 2016; and corresponding international
counterparts.

Biosurgery

Synvisc is protected by U.S. Patent Nos. 5,143,724 which expires July 9, 2010; 5,399,351 which expires March 21, 2012; and corresponding
international counterparts. Seprafilm is protected by U.S. Patent Nos. 5,017,229 which expires May 21, 2008; 5,527,893 which expires June 18, 2013; 6,235,726 which expires
September 18, 2007; and corresponding international counterparts.

Diagnostics/Genetics

Diagnostic dipstick products are protected by U.S. Patent Nos. 5,712,172, which expires April 18, 2015; 6,194,221 which expires November 3,
2017; and corresponding international counterparts.

Genetic
testing services, e.g. for Cystic Fibrosis, are protected by U.S. Patent Nos. 5,585,330 and 5,834,181; which expire July 28, 2014; 5,849,483; which expires
December 15, 2015; 5,882,856; which expires March 16, 2016; 6,207,372; which expires June 6, 2016; and corresponding international counterparts.

In
addition, a portion of our proprietary position is based upon patents that we have licensed from others either through collaboration or traditional license agreements, including
patents relating to:



These
collaboration and license agreements generally require us to share profits with our collaborative partners or pay royalties to our licensors upon commercialization of products
covered by the licensed technology.

16

---





Generally, patents issued in the United States are effective for:



In
some cases, the patent term can be extended to recapture a portion of the term lost during FDA regulatory review. The duration of foreign patents varies in accordance with local law.

We
also rely on trade secrets, proprietary know-how and continuing technological innovation to develop and maintain a competitive position in our product areas. We require our employees,
consultants and corporate partners who have access to our proprietary information to sign confidentiality agreements.

Our
patent position and proprietary technology are subject to certain risks and uncertainties. We have included information about these risks and uncertainties under the subheading
"Factors Affecting Future Operating Results" in "Management's Discussion and Analysis of Genzyme Corporation and Subsidiaries' Financial Condition and Results of Operations" below. We encourage you to
read that discussion, which we are incorporating into this section by reference.

Our
products and services are sold around the world under brand-name trademarks and service marks. Trademark protection continues in some countries as long as the mark is used; in other
countries, as long as it's registered. Registrations generally are for fixed, but renewable, terms. We consider our registered trademarks Genzyme®, Cerezyme®,
Ceredase®, Fabrazyme®, Thyrogen®, Aldurazyme®, Myozyme®, Renagel®, Thymoglobulin®, Campath®,
Clolar®, Synvisc®, Carticel®, MACI®, Seprafilm®, Sepragel®, Seprapack®, Sepramesh®,
Hylaform®, Hylashield®, Hylasome®, Captique®, Epicel®, Contrast®,
OSOM®, N-geneous®, GlyPro®, InSight®, AFP3®, AFP4®, and Hectorol®, together with our trademarks,
VERIGEN, Lymphoglobuline, Cholestagel, CF87, Sepra, Hylashield Nite, SAGE, LongSAGE and
SPHERE, in the aggregate, to be of material importance to our business.

Government Regulation

Regulation by governmental authorities in the United States and other countries is a significant factor in the development, manufacture, commercialization and
reimbursement of our products and services.

FDA Regulation

Most of our products and services require approval from the FDA and corresponding agencies in other countries before they can be marketed. In the United States,
we market products that the FDA classifies as either "drugs," "biologics" or "devices." The activities required before drugs or biologics may be marketed in the United States include:



17

---





As
part of product approval, the manufacturer of the product must undergo a pre-approval Good Manufacturing Practices inspection (for a drug or biologic) from the FDA. Since any approval granted by
the FDA is both site and process specific, any material change by a company in the manufacturing process, equipment or location may necessitate additional FDA review and approval.

In
addition, the FDA may grant accelerated approval for drugs and biologics on the basis of a surrogate endpoint reasonably likely to predict clinical benefit. In such cases, we are
required to conduct post-approval clinical studies to confirm the clinical benefit of the surrogate endpoint that was the basis of the accelerated approval. These clinical studies require the
collection of additional data before full approval will be given and can often be long-term commitments. Although the FDA has not historically invoked its authority to withdraw an accelerated
approval, it may do so. We currently have a number of products approved under the accelerated approval mechanism.

Products
that are classified as devices also require some form of FDA approval prior to marketing. Devices are classified as Class I, II or III, depending upon the information
available to assure their safety and effectiveness. In general, Class I and Class II devices are devices whose safety and effectiveness can reasonably be assured through general or
specific controls, respectively. Class III devices are life sustaining, life supporting, are of substantial importance in preventing impairment to health or pose an unreasonable risk of adverse
effect. They are implantable devices or new devices which have been found not to be substantially equivalent to legally marketed devices. The steps required for approval of a Class III device
include:



Typically,
clinical testing of devices involves initial testing to evaluate safety and feasibility and expanded trials to collect sufficient data to prove safety and effectiveness. In
addition, the procedures and the facilities used to manufacture the device are subject to review and approval by the FDA.

A
device (other than a Class III device) that is proven to be substantially equivalent to a device marketed prior to May 28, 1976, when government regulations for devices
were first introduced, can be marketed after clearance of a 510(k) application rather than the filing of an IDE application and a PMA. The 510(k) application must contain a description of the device,
its methods of manufacture and quality control procedures and the results of testing to demonstrate that the device is substantially equivalent to the device already marketed.

The
time and expense required to perform the clinical testing necessary to obtain FDA approval for regulated products can frequently exceed the time and expense of the research and
development initially required to create the product. Even after initial FDA approval has been obtained, we could be required to conduct further studies to provide additional data on safety or
efficacy or, should we desire, to gain approval for the use of a product as a treatment for additional clinical indications. In addition, use of these products during testing and after marketing
approval has been obtained could reveal side effects which, if serious, could limit uses, or in the most serious cases, result in a market withdrawal of the product or expose us to product liability
claims.

18

---



Regulation Outside of the United States

For marketing outside the United States, we are subject to foreign regulatory requirements governing human clinical testing and marketing approval for our
products. These requirements vary by jurisdiction, differ from those in the United States and may require us to perform additional pre-clinical or clinical testing regardless of whether FDA approval
has been obtained. The amount of time required to obtain necessary approvals may be longer or shorter than that required for FDA approval. In many countries outside of the United States, coverage,
pricing and reimbursement approvals are also required.

Our
initial focus for obtaining marketing approval outside the United States is typically the European Union. European Union regulations and directives generally classify health care
products either as medicinal products, medical devices orin vitrodiagnostics. For medicinal products, marketing approval may be sought using either
the centralized procedure of the EMEA or the decentralized, mutual recognition process. The centralized procedure, which is mandatory for biotechnology derived products, results in a recommendation in
all member states, while the European Union mutual recognition process involves country by country approval.

European
Union regulations for products classified as medical devices have been implemented. Devices, such as our Sepra products, must receive market approval through a centralized
procedure, in which the device receives a CE Mark allowing distribution to all member states of the European Union. The CE Mark certification requires us to receive International Standards
Organization (ISO) certification for each facility involved in the manufacture or distribution of the device. This certification comes only after the development of an all inclusive quality system,
which is reviewed for compliance to International Quality Standards by a licensed "Notified Body" working within the European Union. After certification is received, a product dossier is reviewed that
attests to the product's compliance with European Union directive 93/42 EEC for medical devices. Only after this point is a CE Mark granted.

Other Government Regulation

Good Manufacturing Practices.All facilities and manufacturing techniques used for the manufacture of Genzyme's products must comply with
applicable FDA regulations governing the production of pharmaceutical products known as "Good Manufacturing Practices."

Orphan Drug Act.The Orphan Drug Act provides incentives to manufacturers to develop and market drugs for rare diseases and conditions
affecting fewer than 200,000 persons in the United States at the time of application for orphan drug designation. The first developer to receive FDA marketing approval for an orphan drug is entitled
to a seven year exclusive marketing period in the United States for that product. However, a drug that the FDA considers to be clinically superior to, or different from, another approved orphan drug,
even though for the same indication, may also obtain approval in the United States during the seven year exclusive marketing period. We believe that the commercial success of our orphan drug products
depend more significantly on the associated safety and efficacy profile and on the price relative to competitive or alternative treatments and other marketing characteristics of each product than on
the exclusivity afforded by the Orphan Drug Act. Additionally, these products may be protected by patents and other means.

Legislation
similar to the Orphan Drug Act has been enacted in other countries outside of the United States, including the European Union. The orphan legislation in the European Union is
available for therapies addressing conditions that affect five or fewer out of 10,000 persons. The market exclusivity period is for ten years, although that period can be reduced to six years if, at
the end of the fifth year, available evidence establishes that the product is sufficiently profitable not to justify maintenance of market exclusivity.

19

---



Regulation of Diagnostic Testing Services.The Clinical Laboratories Improvement Act of 1967, as amended in 1988 (CLIA) provides for the
regulation of clinical laboratories by the United States Department of Health and Human Services (HHS). All of our clinical laboratories are CLIA approved, licensed by the College of American
Pathologists and certified by the appropriate state agencies. CLIA regulates virtually all clinical laboratories by requiring they be certified by the federal government and comply with various
operational, personnel and quality requirements intended to ensure that their clinical laboratory testing services are accurate, reliable and timely. CLIA does not preempt state laws that are more
stringent than federal law. For example, state laws may require additional personnel qualifications, quality control, record maintenance and/or proficiency testing.

In
the past, the FDA has claimed regulatory authority over laboratory-developed tests, but has exercised enforcement discretion in not regulating most laboratory-developed tests
performed by high complexity CLIA-certified laboratories. In December 2000, the HHS's Secretary's Advisory Committee on Genetic Testing recommended that the FDA be the lead federal agency to
regulate genetic testing. In late 2002, a new HHS Secretary's Advisory Committee on Genetics, Health and Society was appointed to replace the prior Advisory Committee, but it has not yet made any
final recommendations. In the meantime, the FDA is considering revising its regulations on analyte specific reagents, which are used in laboratory-developed tests, including laboratory-developed
genetic testing. Increased FDA regulation of the reagents used in laboratory-developed testing could lead to increased costs and delays in introducing new tests, including genetic tests. In addition,
the Medicare and Medicaid programs provide a substantial portion of reimbursement for our diagnostic products. Whether these programs pay for any particular test, and the amounts that they pay, may be
unilaterally changed at any time.

Regulation of Diagnostic Products.The FDA has regulatory responsibility over instruments, test kits, reagents and other devices used to
perform diagnostic testing by clinical laboratories. Like other medical devices, in vitrodiagnostic (IVD) products are divided into three classes
according to the level of regulatory control needed to assure safety and effectiveness. Genzyme's current IVD products are either Class I or Class II, and are either exempt from
pre-market notification or require a 510(k) submission.

Regulation of Gene Therapy Products.In addition to FDA requirements, the National Institutes of Health have established guidelines
providing that transfers of recombinant DNA into human subjects at NIH laboratories or with NIH funds must be approved by the NIH Director. The NIH has established the
Recombinant DNA Advisory Committee to review gene therapy protocols. We expect that many of our gene therapy protocols will be subject to review by the Recombinant DNA Advisory Committee. In the
United Kingdom, our gene therapy protocols will be subject to review by the Gene Therapy Advisory Committee and in Germany, these protocols will be subject to review by the Commission for Somatic Cell
Therapy. Greater government regulation of gene therapy products may lead to regulatory delays, increased development costs, and negative public perception of the gene therapy products we are
developing.

Other Laws and Regulations.Our operations are or may be subject to various federal, state and local laws, regulations and recommendations
relating to the marketing of products and relationships with treating physicians, data protection, safe working conditions, laboratory and manufacturing practices, the export of products to certain
countries, and the purchase, storage, movement, use and disposal of hazardous or potentially hazardous substances used in connection with our research work and manufacturing operations, including
radioactive compounds and infectious disease agents. Although we believe that our safety procedures comply with the standards prescribed by federal, state and local regulations, the risk of
contamination, injury or other accidental harm cannot be eliminated completely. In the event of an accident, we could be held liable for any damages that result and any liabilities could exceed our
resources.

20

---



Sales, Marketing and Product Pricing

We are subject to various federal and state laws pertaining to health care "fraud and abuse," including anti-kickback and false claims statutes. Anti-kickback
laws make it illegal for a prescription drug manufacturer to solicit, offer, receive, or pay any remuneration in exchange for, or to induce, the referral of business, including the purchase or
prescription of a particular drug. The federal government has published regulations that identify "safe harbors" or exemptions for certain payment arrangements that do not violate the anti-kickback
statutes. Genzyme seeks to comply with the safe harbors where possible. Due to the breadth of the statutory provisions, and the lack of guidance in the form of regulations or court decisions
addressing some industry activities, it is possible that our practices might be challenged under anti-kickback or related laws. False claims laws prohibit anyone from knowingly and willingly
presenting, or causing to be presented for payment to third-party payors, including Medicare and Medicaid, claims for reimbursed drugs or services that are false or fraudulent, claims for items or
services not provided as claimed, or claims for medically unnecessary items or services. Promotion of drugs for uses outside their labeled indications, so called "off-label" promotion, recently has
led to several financially significant settlement agreements under the False Claims Act.

Our
activities relating to the sale and marketing of, and price reporting for, our products are subject to scrutiny under these fraud and abuse laws. Violations of these laws may result
in criminal and/or civil sanctions, including fines and civil monetary penalties, as well as possible exclusion from federal health care programs, including Medicare and Medicaid. Federal and state
authorities are paying increased
attention to the pharmaceutical and biotechnology industries in enforcement of these laws, and we have been named in several legal proceedings alleging violations.

We
participate in the Medicaid rebate program. Participation in this program has included extending comparable discounts under the Public Health Service (PHS) pharmaceutical pricing
program. Under the Medicaid rebate program, we pay a rebate for each unit of drug product that is reimbursed by Medicaid. The amount of the rebate for each product is set by law as a minimum 15.1% of
the average manufacturer price (AMP) of that product, or if it is greater, the difference between AMP and the best price available from Genzyme to any customer. The rebate amount also includes an
inflation adjustment if AMP increases greater than inflation. The PHS pricing program extends discounts comparable to the Medicaid rebate to a variety of community health clinics and other entities
that receive health services grants from the PHS, as well as hospitals that serve a disproportionate share of poor Medicare and Medicaid beneficiaries. The rebate amount is recomputed each quarter
based on our reports of our current AMP and best price for each of our products. The terms of our participation in the Medicaid program impose an obligation to correct the prices reported in previous
quarters, if necessary. Any such corrections could result in an overage or underage in our rebate liability for past quarters, depending on the nature of the correction. In addition to retroactive
rebates (and interest, if any), if we were found to have knowingly submitted false information to the government, in addition to other penalties available to the government, the statute provides for
civil monetary penalties for each claim containing false information.

The
Medicaid Prescription Drug, Improvement and Modernization Act of 2003 (the "MMA") has significantly changed how Medicare pays for certain of our products, most prominently Cerezyme,
Fabrazyme and Synvisc. As of January 1, 2005, Medicare pays for products covered by the Part B benefit based on the average selling price (ASP) plus 6%. Medicare had previously paid for
these products based on 95% of the average wholesale price (AWP). We do not anticipate the change from the AWP to the ASP system to have a material adverse impact on our ability to obtain adequate
reimbursement for our products.

Part
D of the MMA also has made Medicare coverage available for the first time for a number of drugs, including Renagel and oral Hectorol beginning in 2006. Part D is administered by
private vendors under contract with the United States government. Each vendor establishes it own Part D

21

---



formulary
for prescription drug coverage and pricing, which the vendor may modify from time-to-time. Renagel and Hectorol currently are well-positioned on the majority of Medicare formularies.

Employees

As of December 31, 2005, we, together with all of our consolidated subsidiaries, had approximately 8,200 employees worldwide.

Financial Information Regarding Segment Information

We have provided the information required by Item 101(b) of Regulation S-K in Note R., "Segment Information," to our Consolidated Financial
Statements in the 2005 Genzyme Corporation Annual Report set forth in Exhibit 13.1 to this Annual Report on Form 10-K. We are incorporating that information into this section by
reference.

Research and Development Costs

We have provided the information required by Item 101(c)(1)(xi) of Regulation S-K in Part II, Item 8, "Financial Statements and Supplementary
Data," and specifically in the Genzyme Corporation and Subsidiaries Consolidated Statements of Operations and Comprehensive Income and in Note J., "Investments in Marketable Securities and
Strategic Equity Investments" to our Consolidated Financial Statements in the 2005 Genzyme Corporation Annual Report set forth in Exhibit 13.1 to this Annual Report on Form 10-K. We are
incorporating that information into this section by reference.

Sales by Geographic Area, Significant Customers and Products

We have provided the information required by Items 101(c)(1)(i) and (vii) and 101(d) of Regulation S-K in the 2005 Genzyme Corporation Annual
Report under the heading "Management's Discussion and Analysis of Genzyme Corporation and Subsidiaries' Financial Condition and Results of Operations" and in Note R., "Segment Information," to
our Consolidated Financial Statements set forth in Exhibit 13.1 to this Annual Report on Form 10-K. We are incorporating that information into this section by reference.

Available Information

We file electronically with the SEC our annual report on Form 10-K, our quarterly reports on Form 10-Q, and current reports on Form 8-K
pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934. You may read or copy any materials we file with the SEC at the SEC's Public Reference Room at 100 F Street,
N.E., Washington, D.C. 20549. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330. The SEC also maintains an Internet site that contains
reports, proxy and information statements, and other information about issuers that file reports electronically with the SEC. The address of that site is http://www.sec.gov.

You
may obtain a free copy of our annual report on Form 10-K, our quarterly reports on Form 10-Q and current reports on Form 8-K, and amendments to those reports, as
soon as reasonably practicable after we file them with the SEC, on our website at http://www.genzyme.com or by contacting our Investor Relations department at 1-617-252-7570. The reference to our
website is not intended to incorporate information on our website into this document by reference.

ITEM 1A. RISK FACTORS

We incorporate our disclosure related to risk factors into this section by reference from the 2005 Genzyme Corporation Annual Report under the heading
"Management's Discussion and Analysis of

22

---



Genzyme
Corporation and Subsidiaries' Financial Condition and Results of OperationsFactors Affecting Future Operating Results," which is included in Exhibit 13.1 to this Annual
Report on Form 10-K.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

ITEM 2. PROPERTIES

Our operations are conducted in manufacturing, warehousing, pilot plant, clinical laboratories, and research and office facilities that are located principally
in: the United States; the United Kingdom; the Republic of Ireland; The Netherlands; Belgium; France; Canada; Switzerland; and Germany.

We
lease all of our facilities except for certain facilities in: Geel, Belgium (land subject to 99 year leasehold); Haverhill and Maidstone, England; Boston, Massachusetts (land
subject to 65 year leasehold); Framingham and Waltham, Massachusetts; Ridgefield, New Jersey; Santa Fe, New Mexico; Waltham, Massachusetts; and Waterford, Ireland (land subject to
999 year leasehold).

Our
principal manufacturing facilities are used for the large-scale production of therapeutic proteins and enzymes, including Cerezyme, Fabrazyme, Myozyme and Thyrogen, renal products
and immunosuppressive agents, including Renagel, Thymoglobulin and Lymphoglobuline, biomaterials, including Synvisc and the Sepra family of anti-adhesion products, bulk hyaluronic acid, cell
processing services, including Carticel and Epicel, genetic testing services, and diagnostic test kits and reagents. The facilities also are used for the receipt of contract manufactured products and
materials for Hectorol, WelChol, Renagel, Campath and Clolar.

Our
administrative activities are concentrated at facilities we have leased in Cambridge and Framingham, Massachusetts and San Antonio, Texas in the United States; Naarden, The
Netherlands; and Tokyo, Japan. Our sales and marketing activities are principally located in Cambridge, Massachusetts and in sales offices located in major cities throughout the world. We conduct our
product research and development activities primarily at our laboratory facilities in Framingham and Waltham, Massachusetts; San Antonio, Texas; and San Diego, California in the United States and at
our Cambridge, U.K. facility. Leases for our facilities contain typical commercial lease provisions, including renewal options, rent escalators and tenant responsibility for operating expenses. We
believe that we have, or are in the process of developing or acquiring, adequate manufacturing capacity to support our requirements for the next several years.

Renal

We manufacture the majority of our supply requirements for sevelamer hydrochloride, the active ingredient in Renagel, at our facilities in Haverhill, England. We
also operate a manufacturing facility in Waterford, Ireland for use in manufacturing the tablet formulation of Renagel. All of our Renagel manufacturing facilities are operational, and have received
all European and United States approvals material to such operations. We contract out the manufacturing and fill-finish work for the capsule
formulation of Hectorol. We are in the process of evaluating options to obtain regulatory approval and secure the supply of Hectorol filled in vials instead of ampules.

Therapeutics

We manufacture Cerezyme, Fabrazyme and Myozyme at our multi-product manufacturing facility in Allston, Massachusetts. This facility, which we own and which
contains extensive sterile filling capacity, is built on land that we hold under a 65-year lease, which expires in May 2057. We manufacture Thyrogen and Myozyme in our small-scale manufacturing
facility in Framingham,

23

---



Massachusetts
and final drug product at our Allston facility. In 2005, we commenced the design and build-out of perfusion capacity at our Geel, Belgium facility to provide back-up and expansion to our
Allston bulk capacity and purification systems.

At
our Waterford, Ireland facility, we are installing new fill-finish capabilities for therapeutic proteins. We completed the qualification batches for the first product to be
manufactured at the facility and are anticipating an inspection by the FDA in the first half of 2006. We anticipate transferring and qualifying additional products during 2006 after securing approvals
for supplying such products commercially.

Transplant

We manufacture Thymoglobulin and Lymphoglobuline at a leased facility in Lyon, France, and maintain administrative offices nearby.

Biosurgery

We produce Synvisc and other hyaluronan-based products in a manufacturing facility located in Ridgefield, New Jersey. We produce bulk hyaluronic acid and the
Sepra family of products at commercial scale in our manufacturing facility in Framingham, Massachusetts.

Diagnostics/Genetics

Our diagnostic test kits and reagents are produced in manufacturing facilities in San Diego, California, Cambridge, Massachusetts and Russelsheim, Germany.

We
produce diagnostic enzymes and other fermentation products in a multi-purpose fermentation and purification facility that we own in Maidstone, England. We conduct research and
development and support sales and marketing efforts in our San Diego, California and Cambridge, Massachusetts facilities and at our leased facility in West Malling, England.

Our
genetic and oncology testing business primarily conducts operations in clinical laboratory and administrative facilities we own in Santa Fe, New Mexico and lease in Westborough,
Massachusetts; New York City and Yonkers, New York; Tampa, Florida; and Los Angeles, Orange, and Monrovia, California.

ITEM 3. LEGAL PROCEEDINGS

We periodically become subject to legal proceedings and claims arising in connection with our business.

Four
lawsuits have been filed against us regarding the exchange of all of the outstanding shares of Biosurgery Stock for shares of Genzyme Stock in connection with the elimination of our
tracking stocks in July 2003. Each of the lawsuits is a purported class action on behalf of holders of Biosurgery Stock. The first case, filed in Massachusetts Superior Court in
May 2003, alleged a breach of the implied covenant of good faith and fair dealing in our charter and a breach of our board of directors' fiduciary duties. The plaintiff in this case sought an
injunction to adjust the exchange ratio for the tracking stock exchange. The Court dismissed the complaint in November 2003, but the plaintiff has appealed this dismissal. This appeal was
argued before the Massachusetts Appeals Court in March 2005 and we are awaiting the Appeals Court's ruling. Two substantially similar cases were filed in Massachusetts Superior Court in August
and October 2003. These cases were consolidated in January 2004, and in July 2004, the consolidated case was stayed pending disposition of a fourth case, which was filed in the
U.S. District Court for the Southern District of New York in June 2003. The complaint initially alleged violations of federal securities laws, common law fraud, and a breach of the
merger agreement with Biomatrix, Inc., or Biomatrix, in addition to the state law claims contained in the other cases. The

24

---



plaintiffs
initially sought an adjustment to the exchange ratio, the rescission of the acquisition of Biomatrix, and unspecified compensatory damages. In November 2005, the plaintiffs in this
case dropped all of the claims alleged in the initial complaint relating to the initial issuance of Biosurgery Stock and the acquisition of Biomatrix, and narrowed the putative class to include only
those individuals who held Biosurgery Stock on May 8, 2003. We have filed a motion to dismiss the amended complaint and to oppose the class certification. Discovery in this case has been put on
hold pending resolution of these motions. We believe each of these cases is without merit and continue to defend against them vigorously.

We
are not able to predict the outcome of the pending legal proceeding listed here, or other legal proceedings, or estimate with certainty the amount or range of any possible loss we
might incur if we do not prevail in the final, non-appealable determinations of such matters. Therefore, we have not accrued any amounts in connection with these potential contingencies. We cannot
provide you with assurance that the legal proceeding listed here, or other legal proceedings, will not have a material adverse impact on our financial condition or results of operations.

ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

None.

EXECUTIVE OFFICERS OF THE REGISTRANT

Set forth below is a list of individuals that are currently serving as our executive officers, or who served in such capacity during the fiscal year ended
December 31, 2005:

|Name                      |  | Age |  | Title                                                                                    
|------------------------- |  | --- |  | -----------------------------------------------------------------------------------------
|Henri A. Termeer          |  | 60  |  | Chairman of the Board of Directors; President and Chief Executive Officer                
|Earl M. Collier, Jr.      |  | 58  |  | Executive Vice President, Cardiovascular and Oncology                                    
|Zoltan A. Csimma          |  | 64  |  | Chief Human Resources Officer; Senior Vice President                                     
|Georges Gemayel, Ph.D.    |  | 45  |  | Executive Vice President, Therapeutics                                                   
|Richard A. Moscicki, M.D. |  | 54  |  | Chief Medical Officer; Senior Vice President, Clinical, Medical and Regulatory Affairs   
|Alan E. Smith, Ph.D.      |  | 60  |  | Chief Scientific Officer; Senior Vice President, Research                                
|Sandford D. Smith         |  | 58  |  | Senior Vice President; President, International Group                                    
|Peter Wirth               |  | 55  |  | Chief Legal Officer; Executive Vice President, Legal and Corporate Development; Secretary
|Michael S. Wyzga          |  | 51  |  | Chief Financial and Accounting Officer; Executive Vice President, Finance                

Mr. Termeerhas served as our President and a Director since October 1983, as Chief Executive Officer since
December 1985 and as Chairman of the Board of Directors since May 1988. For ten years prior to joining Genzyme, Mr. Termeer worked for Baxter International
Laboratories, Inc., a manufacturer of human health care products. Mr. Termeer is a director of ABIOMED, Inc. and a trustee of Hambrecht & Quist Healthcare Investors and
Hambrecht & Quist Life Sciences Investors.

Mr. Collierhas served as Executive Vice President since July 1997 and since August 2003 has had responsibility for
our Oncology and Cardiovascular businesses. He joined Genzyme in January 1997 as Senior Vice President, Health Systems, and served as Executive Vice President, Surgical Products and

25

---



Health
Systems from July 1997 until June 1999. He served as President of our former Genzyme Surgical Products division from June 1999 until December 2000.
Mr. Collier was also responsible for our former Genzyme Tissue Repair division from December 1999 to December 2000. From December 2000 until August 2003
Mr. Collier served as President of our Genzyme Biosurgery business unit. Prior to joining us, Mr. Collier was President of Vitas HealthCare Corporation (formerly Hospice Care
Incorporated), a provider of health care services, from October 1991 until August 1995. Prior to that, Mr. Collier was a partner in the Washington, D.C. law firm of Hogan &
Hartson, which he joined in 1981. Mr. Collier is a director of Covalent Group, Inc., a contract research organization which provides independent clinical trial and product development
services to the pharmaceutical, biotechnology and medical devices industries.

Mr. Csimmahas held the title Senior Vice President and Chief Human Resources Officer since March 1, 2006. He joined us in
July 2000 as Senior Vice President, Human Resources. Prior to joining Genzyme, he served as Vice President, Human Resources of Wyeth Ayerst Research, a pharmaceutical research organization,
from August 1998 to July 2000. During that time, Mr. Csimma also served as Site Head, Genetics Institute, for Wyeth Ayerst. From May 1988 to August 1998, he served
as Vice President, Human Resources and Operations of Genetics Institute, Inc., a biotechnology company, which was integrated into Wyeth Ayerst in March 1998.

Dr. Gemayeljoined us in August 2003 as Executive Vice President with responsibility for our Renal, Therapeutics and
Transplant business units. For sixteen years prior to joining Genzyme, Dr. Gemayel worked for Hoffmann-LaRoche, a leading healthcare company, where he served most recently from July 2000
until August 2003 as Vice President of the United States Specialty Care unit, and from January 1998 until July 2000 as General Manager of Hoffmann-LaRoche Portugal.

Dr. Moscickijoined us in March 1992 as Medical Director, became Vice President, Medical Affairs in early 1993 and was named
Vice President, Clinical, Medical and Regulatory Affairs in December 1993.
In September 1996 he became Senior Vice President, Clinical, Medical and Regulatory Affairs and Chief Medical Officer. Since 1979, he has also been a physician staff member at the Massachusetts
General Hospital and a faculty member at the Harvard Medical School.

Dr. Alan Smithjoined us in August 1989 as Senior Vice President, Research and became Chief Scientific Officer in
September 1996. Prior to joining Genzyme, he served as Vice PresidentScientific Director of Integrated Genetics, Inc., from November 1984 until its acquisition by us
in August 1989. From October 1980 to October 1984, Dr. Smith was head of the Biochemistry Division of the National Institute for Medical Research, Mill Hill, London,
England and from 1972 to October 1980, he was a member of the scientific staff at the Imperial Cancer Research Fund in London, England.

Mr. Sandford Smithhas served as Senior Vice President since January 2003 and has served as President of our International
business since January 2000. From January 1998 until January 2000 he served as President of our Therapeutics business unit. Mr. Smith joined Genzyme in April 1996
and until January 1998 was Vice President and General Manager of our International business and President of our Specialty Therapeutics business. From June 1988 until June 1996,
Mr. Smith was President and Chief Executive Officer of Repligen Corporation. Before joining Repligen Corporation, Mr. Smith spent twelve years at Bristol-Myers Squibb in positions of increasing
responsibility in their International group.

Mr. Wirthjoined us in January 1996 and has served as Executive Vice President and Chief Legal Officer since
September 1996 with responsibility for our corporate development and legal activities. From 2001 through October 2005, Mr. Wirth had responsibility for our drug discovery and
development business. In addition, from September 1996 until June 2003, Mr. Wirth was responsible for our Oncology business. Mr. Wirth is also a director of EPIX
Pharmaceuticals, Inc., a developer of contrast agents for magnetic resonance imaging.

26

---



Mr. Wyzgahas served as Executive Vice President, Finance since May 2003, as Chief Accounting Officer since
January 1999 and as Chief Financial Officer since July 1999. He joined us in February 1998 as Vice President and Corporate Controller and served as Senior Vice President,
Corporate Controller from January 1999 until July 1999. He served as Senior Vice President, Finance from July 1999 until May 2003. From February 1997 to
February 1998 Mr. Wyzga served as Chief Financial Officer of Sovereign Hill Software, Inc., a software company, and from 1991 to 1997 held various senior management positions with
CACHELINK Corporation and Lotus Development Corporation. Mr. Wyzga is also director of Altus Pharmaceuticals Inc., a developer of protein therapeutics.

27

---





PART II

ITEM 5.    MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY  SECURITIES

Effective July 1, 2003, we eliminated our tracking stock capital structure by exchanging, in accordance with the provisions of our charter, each share of
Biosurgery Stock for 0.04914 of a share of Genzyme General Stock and each share of Molecular Oncology Stock for 0.05653 of a share of Genzyme General Stock. Options and warrants to purchase shares of
Biosurgery Stock and options to purchase shares of Molecular Oncology Stock were converted into options and warrants to purchase shares of Genzyme General Stock. Effective July 1, 2003, we have
one outstanding series of common stock. From July 1, 2003 through May 27, 2004, we referred to our outstanding series of common stock as Genzyme General Stock. On May 27, 2004,
our shareholders approved an amendment to our charter that eliminated the designation of separate series of common stock, resulting in 690,000,000 authorized shares of a single series of stock, which
we now refer to as Genzyme Stock.

The
tracking stocks were intended to reflect the value and track the performance of our three former divisions. Through June 30, 2003, all three series of our common stock were
traded on the over-the-counter market and prices were quoted on The NASDAQ® National Market system under the symbols "GENZ," "GZBX" and "GZMO." Since July 1, 2003, our only
outstanding series of common stock has traded under the symbol "GENZ".

As
of March 1, 2006, there were 3,271 stockholders of record of Genzyme Stock.

The
following table sets forth, for the periods indicated, the high and low sale price of Genzyme Stock as reported by NASDAQ.

High

Low2005:First Quarter

$
61.40

$
55.15Second Quarter


65.13


55.51Third Quarter


76.17


58.61Fourth Quarter


77.82


66.622004:First Quarter

$
58.08

$
44.73Second Quarter


49.30


40.67Third Quarter


57.13


44.14Fourth Quarter


59.14


49.25


We
have never paid any cash dividends on any series of our common stock and we do not anticipate paying cash dividends in the foreseeable future.

We
incorporate information regarding the securities authorized for issuance under our equity compensation plans into this section by reference from the section entitled "Equity Plans" in
the proxy statement for our 2006 annual meeting of shareholders.

Issuer Purchases of Equity Securities

We did not make any purchases of our common stock during the three months ended December 31, 2005, which is the fourth quarter of our fiscal year.

ITEM 6.    SELECTED FINANCIAL DATA

We incorporate our Selected Financial Data into this section by reference from the 2005 Genzyme Corporation Annual Report under the heading "Genzyme Corporation
and SubsidiariesConsolidated Selected Financial Data," which is included in Exhibit 13.1 to this Annual Report on Form 10-K.

28

---



ITEM 7.    MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

We incorporate our Management's Discussion and Analysis of Financial Condition and Results of Operations into this section by reference from the 2005 Genzyme
Corporation Annual Report under the heading "Management's Discussion and Analysis of Genzyme Corporation and Subsidiaries' Financial Condition and Results of Operations," which is included in
Exhibit 13.1 to this Annual Report on Form 10-K.

ITEM 7A.    QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

We incorporate our disclosure related to market risk into this section by reference from the 2005 Genzyme Corporation Annual Report under the headings
"Management's Discussion and Analysis of Genzyme Corporation and Subsidiaries' Financial Condition and Results of OperationsMarket Risk," "Interest Rate Risk,"
"Foreign
Exchange Risk" and "Equity Price Risk," which is included in Exhibit 13.1 to this Annual Report on Form 10-K.

ITEM 8.    FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

We incorporate the financial statements filed as part of this Annual Report on Form 10-K into this section by reference from the Genzyme Corporation and
Subsidiaries Consolidated Financial Statements and notes thereto included in Exhibit 13.1 to this Annual Report on Form 10-K.

ITEM 9.    CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None.

ITEM 9A.    CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures

At the direction of our Chief Executive Officer and Chief Financial Officer, we evaluated our disclosure controls and procedures and internal control over
financial reporting and concluded that: (1) our disclosure controls and procedures were effective as of December 31, 2005; and (2) no change in internal control over financial
reporting occurred during the quarter ended December 31, 2005 that has materially affected, or is reasonably likely to materially affect, such internal control over financial reporting.

Management's Report on Internal Control Over Financial Reporting

The full disclosure of our management's assessment of the effectiveness of our internal controls over financial reporting as of December 31, 2005 is set
forth in the 2005 Genzyme Corporation Annual Report under the heading "Management's Report on Internal Controls Over Financial Reporting," which is included in Exhibit 13.1 to this Annual
Report on Form 10-K.

Attestation Report of Independent Registered Public Accounting Firm

Our management's assessment of the effectiveness of our internal controls over financial reporting as of December 31, 2005 has been audited by
PricewaterhouseCoopers LLP, an independent registered public accounting firm. The attestation report of PricewaterhouseCoopers LLP is set forth in the 2005 Genzyme Corporation Annual Report under the
heading "Report of Independent Registered Public Accounting Firm," which is included in Exhibit 13.1 to this Annual Report on Form 10-K.

ITEM 9B.    OTHER INFORMATION

None.

29

---



PART III

ITEM 10.    DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

We have adopted a Corporate Code of Conduct, which applies to our directors and all of our employees, including our principal executive officer, principal
financial officer and accounting officer, and controller. A copy is available to you, free of charge, upon written request to the legal department at our corporate offices located at Genzyme Center,
500 Kendall Street, Cambridge, Massachusetts 02142. We intend to make all required disclosures concerning amendments to, or waivers from, this code on the governance page of our website,
www.genzyme.com. Information contained on our website is not part of this document or the documents incorporated by reference into this document.

We
incorporate information regarding our directors and executive officers into this section by reference from the section entitled "Executive Officers of the Registrant" in Part I
of this Annual Report on Form 10-K and the sections entitled "Election of Directors," "Board Meetings and Committees" and "Section 16(a) Beneficial Ownership Reporting Compliance" in the
proxy statement for our 2006 annual meeting of shareholders.

ITEM 11.    EXECUTIVE COMPENSATION

We incorporate information regarding the compensation of our directors and executive officers into this section by reference from the sections entitled "Election
of Directors," "Director Compensation" and "Executive Compensation" in the proxy statement for our 2006 annual meeting of shareholders.

ITEM 12.    SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

We incorporate information regarding the ownership of our securities by our directors, executive officers and 5% stockholders into this section by reference from
the sections entitled "Stock Ownership" and "Equity Plans" in the proxy statement for our 2006 annual meeting of shareholders.

ITEM 13.    CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

We incorporate information regarding transactions with related parties into this section by reference from the section entitled "Certain Relationships and Related
Transactions" in the proxy statement for our 2006 annual meeting of shareholders.

ITEM 14.    PRINCIPAL ACCOUNTING FEES AND SERVICES

We incorporate information regarding our audit committee's pre-approval policies and procedures and the fees paid to our auditors from the section entitled
"Independent Registered Public Accounting Firm" in the proxy statement for our 2006 annual meeting of shareholders.

30

---



PART IV

ITEM 15.    EXHIBITS, FINANCIAL STATEMENT SCHEDULES

(a)(1). FINANCIAL STATEMENTS

We are incorporating the following financial statements (and related notes) of Genzyme Corporation and Subsidiaries into this section by reference from the 2005
Genzyme Corporation Annual Report:

|                                                                                                                    |  | Page*
|------------------------------------------------------------------------------------------------------------------- |  | -----
|Report of Independent Registered Public Accounting Firm                                                             |  | F-65 
|Consolidated Statements of Operations and Comprehensive Income for the Years Ended December 31, 2005, 2004 and 2003 |  | F-67 
|Consolidated Balance Sheets as of December 31, 2005 and 2004                                                        |  | F-69 
|Consolidated Statements of Cash Flows for the Years Ended December 31, 2005, 2004 and 2003                          |  | F-70 
|Consolidated Statements of Stockholders' Equity for the Years Ended December 31, 2005, 2004 and 2003                |  | F-72 
|Notes to Consolidated Financial Statements                                                                          |  | F-75 

---

31

---





(a)(2). FINANCIAL STATEMENT SCHEDULES

The schedule listed below for Genzyme Corporation and Subsidiaries is filed as part of Exhibit 13.1 to this Annual Report on Form 10-K and is
incorporated into this section by reference:

| |                                                         | Page*
| | ------------------------------------------------------- | -----
| | Report of Independent Registered Public Accounting Firm |      
| | Schedule IIValuation and Qualifying Accounts           |      

---

All
other schedules are omitted as the information required is inapplicable or the information is presented in the Genzyme Corporation and Subsidiaries' Consolidated Financial Statements
or notes thereto.

(a)(3). EXHIBITS

The exhibits are listed below under Part IV, Item 15(b) of this Annual Report on Form 10-K.

(b). EXHIBITS

|EXHIBIT NO. |  | DESCRIPTION                                                                                                                                                                                                                                                                       
|----------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|*3.1        |  | Restated Articles of Organization of Genzyme, as amended. Filed as Exhibit 3.1 to Genzyme's Registration Statement on Form 8-A/A filed on May 28, 2004.                                                                                                                           
|*3.2        |  | By-laws of Genzyme, as amended. Filed as Exhibit 3.1 to Genzyme's Form 8-K filed July 1, 2004.                                                                                                                                                                                    
|*4.1        |  | Fourth Amended and Restated Renewed Rights Agreement dated May 28, 2004 between Genzyme and American Stock Transfer & Trust Company, as Rights Agent. Filed as Exhibit 4.1 to Genzyme's Registration Statement on Form
8-A/A filed on May 28, 2004.                               
|*4.2        |  | Securities Purchase Agreement, dated as of April 17, 2001 and amended on September 26, 2001, by and among Novazyme Pharmaceuticals, Inc. and several purchasers. Filed as Exhibit 4.2 to Genzyme's Form 10-Q for the
quarter ended September 30, 2001.                            
|*4.3        |  | Indenture, dated December 9, 2003, between Genzyme and U.S. Bank National Association. Filed as Exhibit 4.1 to Genzyme's Form 8-K filed December 10, 2003.                                                                                                                        
|*4.3.1      |  | First Supplemental Indenture, dated as of May 28, 2004, to Indenture relating to our 1.25% Senior Convertible Notes, dated as of December 9, 2003, between Genzyme and U.S. Bank National Association, as Trustee. Filed as
Exhibit 4.1 to Genzyme's Form 8-K filed June 18, 2004.
|*4.4        |  | Registration Rights Agreement, dated December 9, 2003, between Genzyme and UBS Securities LLC on behalf of itself and several other Initial Purchasers. Filed as Exhibit 10.1 to Genzyme's Form 8-K filed December 10,
2003.                                                      
|*10.1       |  | Lease, dated April 30, 1990, for 64 Sidney Street, Cambridge, Massachusetts between BioSurface Technology, Inc. and Forest City 64 Sidney Street, Inc. Filed as Exhibit 10.22 to BioSurface's Registration Statement on Form
S-1 (File No. 33-55874).                             
|*10.1.1     |  | Amendment to Lease, dated September 11, 1995, to the Lease Agreement dated April 30, 1990 by and between Forest City 64 Sidney Street, Inc. and Genzyme. Filed as Exhibit 10.1.1 to Genzyme's Form 10-K for
2003.                                                                 
|*10.1.2     |  | Second Amendment to Lease, dated March 1, 1996, to the Lease Agreement dated April 30, 1990 by and between Forest City 64 Sidney Street, Inc. and Genzyme. Filed as Exhibit 10.1.2 to Genzyme's Form 10-K for
2003.                                                               
|            |  |                                                                                                                                                                                                                                                                                   

32

---



|*10.1.3 |  | Letter Amendment, dated December 30, 1999, to the Lease Agreement dated April 30, 1990 by and between Forest City 64 Sidney Street, Inc. and Genzyme. Filed as Exhibit 10.1.3 to Genzyme's Form 10-K for 2003.                                                                                                                                                                                   
|------- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|*10.1.4 |  | Fourth Amendment to Lease, dated March 23, 2001, to the Lease Agreement dated April 30, 1990 by and between Forest City 64 Sidney Street, Inc. and Genzyme. Filed as Exhibit 10.1.4 to Genzyme's Form 10-K for
2003.                                                                                                                                                                             
|*10.2   |  | Lease, dated June 1, 1992, for land at Allston Landing, Allston, Massachusetts between Allston Landing Limited Partnership and the Massachusetts Turnpike Authority. Filed as Exhibit 10.9 to Genzyme's Form 10-K for
1993.                                                                                                                                                                      
|*10.3   |  | Commercial Lease, dated December 24, 1998, by and between Aventis Pasteur SA and Imtix-SangStat S.A.S. for Building C5 located at Marcy L'Etoile, Lyon, France. Filed as Exhibit 10.4 to Genzyme's Form 10-K for
2003.                                                                                                                                                                           
|*10.3.1 |  | Amendment to Commercial Lease, dated September 30, 2000, to the Lease dated December 24, 1998, by and between Aventis Pasteur SA and Imtix-SangStat S.A.S. Filed as Exhibit 10.4.1 to Genzyme's Form 10-K for
2003.                                                                                                                                                                              
|10.4    |  | Lease, dated August 28, 2000, for Building D, Cambridge Research Park, Cambridge, Massachusetts, between Genzyme and Kendall Square LLC. Filed herewith.                                                                                                                                                                                                                                         
|*10.4.1 |  | First Amendment to Lease, dated August 1, 2003, to lease dated as of August 28, 2000, by and between Genzyme and Kendall Square LLC. Filed as Exhibit 10.5.1 to Genzyme's Form 10-K for 2004.                                                                                                                                                                                                    
|*10.5   |  | Underlease of 50 Gibson Drive, Kings Hill Business Park, West Malling, Kent, U.K., dated January 19, 2001 by and among Genzyme Limited, Liberty Property Limited Partnership and Kings Hill Estate Management Company
Limited. Filed as Exhibit 10.1 to Genzyme's Form 10-Q for the quarter ended September 30, 2005.                                                                            
|*10.5.1 |  | Deed of Variation of Underlease dated January 19, 2001, and Agreement for Lease, each dated August 22, 2005 by and between Genzyme Limited and Kent City Council (successors to Liberty Property Limited Partnership). Filed
as Exhibit 10.2 to Genzyme's Form 10-Q for the quarter ended September 30, 2005.                                                                                    
|*10.6   |  | Lease, dated September 3, 1990, for the land located at the Industrial Development Authority Industrial Park, County Waterford, Ireland (comprised in folio 4917 & 324IF County Waterford) by and between the Industrial
Development Authority and Bausch & Lomb Ireland. Filed as Exhibit 10.2 to Genzyme's Form 10-Q for the quarter ended September 30, 2001.                                 
|*10.7   |  | Contract for Sale, dated June 25, 2001, for the premises located at the Industrial Development Authority Industrial Park, County Waterford, Ireland, (comprised in folio 4141L County Waterford) by and between
Luxottica Ireland Limited and Genzyme Ireland Limited (f/n/a Gosfend Limited). Filed as Exhibit 10.1 to Genzyme's Form 10-Q for the quarter ended September 30, 2001.            
|*10.8   |  | Deed of Transfer, dated July 2, 2001, between Luxottica Ireland Limited and Genzyme Ireland Limited, related to the Lease dated September 3, 1990 for the premises located at the Industrial Development Authority Industrial
Park, County Waterford, Ireland (comprised in folio 4141L County Waterford). Filed as Exhibit 10.3 to Genzyme's Form 10-Q for the quarter ended September 30, 2001.
|*10.9   |  | Contract for Sale, dated August 2, 2001, for the land located at the Industrial Development Authority Industrial Park, County Waterford, Ireland (comprised in folio 4917 County Waterford) by the Industrial
Development Agency (Ireland) and Genzyme Ireland Limited. Filed as Exhibit 10.4 to Genzyme's Form 10-Q for the quarter ended September 30, 2001.                                   
|*10.10  |  | Lease, dated August 24, 2001, for the land located at the Industrial Development Authority Industrial Park, County Waterford, Ireland (comprised in folio 4917 County Waterford) by the Industrial Development Agency
(Ireland) and Genzyme Ireland Limited. Filed as Exhibit 10.5 to Genzyme's Form 10-Q for the quarter ended September 30, 2001.                                              
|        |  |                                                                                                                                                                                                                                                                                                                                                                                                  

33

---



|*10.11   |  | Partnership Purchase Agreement, dated as of November 20, 2000, between Genzyme, Genzyme Development Corporation II, Genzyme Development Partners, L.P. ("GDP") and each Class A Limited Partner of GDP. Filed as Exhibit
10.24 to Genzyme's Form 10-K for 2000.
|-------- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|*10.12   |  | Agreement and Plan of Merger, dated as of August 6, 2001, among Genzyme, Rodeo Merger Corp. and Novazyme Pharmaceuticals, Inc. Filed as Exhibit 2.1 to Genzyme's Form 8-K filed on August 22, 2001.                                                            
|*10.13   |  | 1997 Equity Incentive Plan, as amended. Filed as Exhibit 10.4 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                                                                                      
|10.14    |  | 1998 Director Stock Option Plan, as amended. Filed herewith.                                                                                                                                                                                                   
|*10.14.1 |  | Form of Nonstatutory Stock Option for grants under Genzyme's 1998 Director Stock Option Plan. Filed as Exhibit 10.5 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                                
|*10.15   |  | 2001 Equity Incentive Plan, as amended. Filed as Exhibit 10.17 to Genzyme's Form 10-K for 2004.                                                                                                                                                                
|*10.15.1 |  | Form of Incentive Stock Option for grants to executive officers under Genzyme's 2001 Equity Incentive Plan. Filed as Exhibit 10.6 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                  
|*10.15.2 |  | Form of Nonstatutory Stock Option for grants to executive officers under Genzyme's 2001 Equity Incentive Plan. Filed as Exhibit 10.7 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                               
|*10.16   |  | 2004 Equity Incentive Plan, as amended. Filed as Exhibit 10.8 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                                                                                      
|*10.16.1 |  | Form of Incentive Stock Option for grants to executive officers under Genzyme's 2004 Equity Incentive Plan. Filed as Exhibit 10.9 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                  
|*10.16.2 |  | Form of Nonstatutory Stock Option for grants to executive officers under Genzyme's 2004 Equity Incentive Plan. Filed as Exhibit 10.10 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                              
|*10.17   |  | 1999 Employee Stock Purchase Plan, as amended. Filed as Exhibit 10.11 to Genzyme's Form 10-Q for the quarter ended June 30, 2005.                                                                                                                              
|*10.18   |  | 1996 Directors' Deferred Compensation Plan, as amended. Filed as Exhibit 10.20 to Genzyme's Form 10-K for 2004.                                                                                                                                                
|*10.19   |  | Executive Employment Agreement, dated as of January 1, 1990, between Genzyme and Henri A. Termeer. Filed as Exhibit 10.32 to Genzyme's Form 10-K for 1990.                                                                                                     
|*10.20   |  | Executive Employment Agreement, dated as of January 1, 1996, between Genzyme and Peter Wirth. Filed as Exhibit 10.1 to Genzyme's Form 10-Q for the quarter ended March 31, 1996.                                                                               
|*10.21   |  | Form of Indemnification Agreement between Genzyme and its executive officers. Filed as Exhibit 10.1 to Genzyme's Form 10-Q for the quarter ended September 30, 2004.                                                                                           
|*10.22   |  | Form of Severance Agreement between Genzyme and its executive officers. Filed as Exhibit 10.2 to Genzyme's Form 10-Q for the quarter ended June 30, 2002.                                                                                                      
|*10.23   |  | Information regarding certain executive compensation matters, including 2006 salaries and incentive bonus targets for Genzyme's named executive officers. Filed with Genzyme's Form 8-K filed on December 5,
2005.                                             
|*10.23.1 |  | Information regarding certain executive compensation matters, including actual 2005 salaries and incentive bonuses for Genzyme's named executive officers. Filed with Genzyme's Form 8-K filed on March 3,
2006.                                               
|*10.24   |  | Collaboration Agreement, dated September 4, 1998, among Genzyme, BioMarin and BioMarin/Genzyme LLC. Filed as Exhibit 10.24 to BioMarin's Registration Statement on Form S-1 (File No. 333-77701).**                                                            
|         |  |                                                                                                                                                                                                                                                                

34

---



|*10.25   |  | Supply Agreement, dated as of November 9, 1999, by and between Cambrex Charles City, Inc. (f/k/a Salsbury Chemicals, Inc.) and GelTex Pharmaceuticals Inc., or GelTex. Filed as Exhibit 10.32 to GelTex's Form 10-K for 1999
(File No. 0-26872).**                                                                                                                                                            
|-------- |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|*10.26   |  | Contract Manufacturing Agreement dated September 14, 2001, as amended on May 15, 2002, between GelTex and The Dow Chemical Company. Filed as Exhibit 10.35 to Genzyme's Form 10-K for 2002.**                                                                                                                                                                                                                 
|*10.26.1 |  | Second Amendment, dated October 9, 2002, to Contract Manufacturing Agreement dated September 14, 2001, between GelTex and The Dow Chemical Company. Filed as Exhibit 10.34.1 to Genzyme's Form 10-K for 2003.**                                                                                                                                                                                               
|*10.26.2 |  | Third Amendment, dated December 8, 2003, to Contract Manufacturing Agreement dated September 14, 2001, between Genzyme and The Dow Chemical Company. Filed as Exhibit 10.34.2 to Genzyme's Form 10-K for 2003.**                                                                                                                                                                                              
|*10.26.3 |  | Fourth Amendment, dated as of July 1, 2004, to Contract Manufacturing Agreement dated September 14, 2001, between GelTex and The Dow Chemical Company. Filed as Exhibit 10.29.3 to Genzyme's Form 10-K for
2004.**                                                                                                                                                                                            
|*10.27   |  | Credit Agreement, dated December 10, 2003, among Genzyme and those of its subsidiaries party thereto, the lenders listed therein, Fleet National Bank, as Administrative Agent, ABN AMRO Bank N.V. as Syndication Agent and
The Bank of Nova Scotia, Citizens Bank of Massachusetts and Wachovia Bank National Association as Co-Documentation Agents. Filed as Exhibit 10.36 to Genzyme's Form 10-K for 2003.
|*10.27.1 |  | First Amendment to Credit Agreement, dated as of June 30, 2004, to Credit Agreement dated December 10, 2003, among Genzyme, SangStat Medical Corporation, each of the financial institutions identified under the caption
"Lenders" on the signature pages and Fleet National Bank as administrative agent for the Lenders. Filed as Exhibit 10.1 to Genzyme's Form 10-Q for the quarter ended June 30, 2004. 
|*10.28   |  | North American Termination and Transition Agreement, dated November 3, 2004, by and between Genzyme and Wyeth. Filed as Exhibit 10.31 to Genzyme's Form 10-K for 2004.**                                                                                                                                                                                                                                      
|13.1     |  | Portions of the 2005 Genzyme Corporation Annual Report incorporated by reference into Parts I, II and IV of this Form 10-K. Furnished herewith.                                                                                                                                                                                                                                                               
|21       |  | Subsidiaries of Genzyme. Filed herewith.                                                                                                                                                                                                                                                                                                                                                                      
|23       |  | Consent of PricewaterhouseCoopers LLP. Filed herewith.                                                                                                                                                                                                                                                                                                                                                        
|31.1     |  | Certification of the Chief Executive Officer pursuant to section 302 of the Sarbanes-Oxley Act of 2002. Filed herewith.                                                                                                                                                                                                                                                                                       
|31.2     |  | Certification of the Chief Financial Officer pursuant to section 302 of the Sarbanes-Oxley Act of 2002. Filed herewith.                                                                                                                                                                                                                                                                                       
|32.1     |  | Certification of the Chief Executive Officer pursuant to section 906 of the Sarbanes-Oxley Act of 2002. Furnished herewith.                                                                                                                                                                                                                                                                                   
|32.2     |  | Certification of the Chief Financial Officer pursuant to section 906 of the Sarbanes-Oxley Act of 2002. Furnished herewith.                                                                                                                                                                                                                                                                                   
|99       |  | Financial Statements and notes thereto of BioMarin/Genzyme LLC as of December 31, 2005 and 2004 (unaudited) and for the years ended December 31, 2005, 2004 (unaudited) and 2003. Filed herewith.                                                                                                                                                                                                             

---

EXECUTIVE COMPENSATION PLANS AND ARRANGEMENTS

Exhibits 10.13 through 10.23.1 above are management contracts or compensatory plans or arrangements in which our executive officers or directors participate.

35

---





SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.

|                     |  | GENZYME CORPORATION
|-------------------- |  | -------------------
|Dated: March 9, 2006 |  | By:                

Pursuant
to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on
the date indicated.

|Name                                          |  | Title                                      |  | Date         
|--------------------------------------------- |  | ------------------------------------------ |  | -------------
|                                              |  |                                            |  |              
|/s/HENRI A. TERMEERHenri A. Termeer           |  | Director and Principal Executive Officer   |  | March 9, 2006
|/s/MICHAEL S. WYZGAMichael S. Wyzga           |  | Principal Financial and Accounting Officer |  | March 9, 2006
|/s/DOUGLAS A. BERTHIAUMEDouglas A. Berthiaume |  | Director                                   |  | March 9, 2006
|Henry E. Blair                                |  | Director                                   |  |              
|/s/GAIL K. BOUDREAUXGail K. Boudreaux         |  | Director                                   |  | March 9, 2006
|/s/ROBERT J. CARPENTERRobert J. Carpenter     |  | Director                                   |  | March 9, 2006
|/s/CHARLES L. COONEYCharles L. Cooney         |  | Director                                   |  | March 9, 2006
|/s/VICTOR J. DZAUVictor J. Dzau               |  | Director                                   |  | March 9, 2006
|/s/CONNIE MACK IIIConnie Mack III             |  | Director                                   |  | March 9, 2006
|Richard F. Syron                              |  | Director                                   |  |              

36

---



QuickLinks