Genzyme Files for European Approval of Synvisc® In Ankle and Shoulder Indications

Seeks to Broaden Use of Product with Expanded Label

August 11, 2006, Genzyme Corp. (Nasdaq: GENZ) announced today that it has filed with the European authority to expand the CE mark for Synvisc® (hylan G-F 20) to include treatment of pain due to osteoarthritis (OA) of the ankle and shoulder. Approval of a new label will provide opportunity to broaden the use of Synvisc beyond its current European-approved use in the knee and hip to the two additional joints.

“Our filing in Europe for approval of Synvisc in the ankle and shoulder reaffirms our commitment to the field of osteoarthritis and to pursuing new medical indications to help patients manage pain from OA,” stated Ann Merrifield, president of Genzyme Biosurgery, the business unit of Genzyme Corp. that manufactures and markets Synvisc. “With approval in the ankle and shoulder, Synvisc will be one of the few viscosupplements available in Europe for treating OA pain in four major joints that is supported by strong clinical data.”

Genzyme’s filing for label expansion of Synvisc contains data from two clinical trials in the ankle and shoulder. The studies were prospective, multi-center, open investigations that took place in several countries throughout Europe. Both studies found treatment with Synvisc to be well-tolerated, and data show that Synvisc significantly decreases pain due to OA in the ankle and shoulder and that the decreased pain effect is maintained for up to six months. Data from the ankle study have been accepted for presentation at the American College of Rheumatology meeting this fall in Washington, D.C.

Genzyme expects the European regulatory review of the Synvisc label expansion to be complete by the end of the year.

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Recently announced data from an independent investigator’s clinical study found Synvisc to be superior in magnitude and duration of pain relief, functional improvement and patient satisfaction to another viscosupplementation product in treating patients with OA of the knee. These independent data were presented last June at the European League Against Rheumatism (EULAR) meeting in Amsterdam, The Netherlands.

Genzyme is utilizing evidence-based medicine in broadening Synvisc label claims that further establish its efficacy and safety. In addition, two meta-analyses in 2004 and 2006 also affirmed the clinical benefit of Synvisc and its class of viscosupplements. These studies were conducted using research methodologies that provide physicians and payers with tools to evaluate new treatments using an evidence-based approach. In addition to its efficacy in relieving OA knee pain, Synvisc, as a non-systemic treatment, has the advantage of avoiding the side effects associated with some non-steroidal anti-inflammatory drugs including the COX-2 inhibitors.

Synvisc is marketed in more than 60 countries and has been used to treat more than 3 million people. Synvisc is currently approved in the United States for treatment of pain due to osteoarthritis of the knee. Genzyme is pursuing a label expansion in the U.S. that would include the hip indication.

About Synvisc

Synvisc is indicated for the treatment of pain due to osteoarthritis (OA) of the knee in patients who have failed to respond adequately to conservative nonpharmacologic therapy and simple analgesics, for example, acetaminophen. Synvisc is currently approved in Europe and Canada to treat pain due to osteroarthritis in both the knee and hip.

In clinical trials, the most commonly reported adverse events were transient local pain, swelling, and/or effusion in the injected knee. In some cases, these symptoms have been extensive. Other side effects such as rash have been reported rarely. Synvisc is contraindicated in patients with known hypersensitivity to hyaluronan products or patients with infections in or around the knee. Healthcare practitioners should exercise caution when using Synvisc in patients allergic to avian proteins, feathers, or egg products; who have evidence of venous or lymphatic stasis in the leg to be treated; or who have severe inflammation in the knee joint to be treated. Patients should be advised to avoid strenuous or prolonged weight-bearing activities after treatment. Strict adherence to aseptic technique must be followed to avoid joint infection. The safety and effectiveness of Synvisc in children and in pregnant or lactating women have not been established. It is unknown whether Synvisc is excreted in human milk.

About Genzyme Corporation

One of the world’s leading biotechnology companies, Genzyme is dedicated to making a major positive impact on the lives of people with serious diseases. This year marks the 25th anniversary of Genzyme’s founding. Since 1981, the company has grown from a small start-up to a diversified enterprise with more than 8,500 employees in locations spanning the globe and 2005 revenues of $2.7 billion. Genzyme has been selected by FORTUNE as one of the “100 Best Companies to Work for” in the United States.

With many established products and services helping patients in more than 80 countries, Genzyme is a leader in the effort to develop and apply the most advanced technologies in the life sciences. The company’s products and services are focused on rare inherited disorders, kidney disease, orthopaedics, cancer, transplant and immune diseases, and diagnostic testing. Genzyme’s commitment to innovation continues today with a substantial development program focused on these fields, as well as heart disease and other areas of unmet medical need.

This press release contains forward-looking statements, including the statements regarding the European regulatory review of the Synvisc label expansion. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in these forward-looking statements. These risks and uncertainties include, among others, that the European regulatory review will not be completed by the end of the year and the risks and uncertainties described in reports filed by Genzyme with the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended, including without limitation the information under the heading “Factors Affecting Future Operating Results” in the Management’s Discussion and Analysis of Financial Condition and Results of Operations section of the Genzyme Quarterly Report on Form 10-Q for the quarter ending June 30, 2006. Genzyme cautions investors not to place substantial reliance on the forward-looking statements contained in this press release. These statements speak only as of the date of this press release, and Genzyme undertakes no obligation to update or revise the statements.

Genzyme® and Synvisc® are registered trademarks of Genzyme Corporation. All rights reserved.

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Maria Cantor

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Genzyme Corporation

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