CAMBRIDGE, MA — June 6, 2006 — Momenta Pharmaceuticals, Inc. (Nasdaq: MNTA), a biotechnology company developing drugs based on its proprietary sugar sequencing technology, today announced that it will hold its Annual Meeting of Stockholders on June 15, 2006 at 9:00 am EDT at the offices of Wilmer Cutler Pickering Hale and Dorr LLP, 60 State Street, Boston, MA. Stockholders of record at the close of business on April 25, 2006 are entitled to vote at the Annual Meeting. Momenta mailed a notice of the Annual Meeting and related proxy materials to stockholders of record on or about May 11, 2006.

About Momenta:
Momenta Pharmaceuticals, Inc. is a biotechnology company specializing in the detailed structural analysis and design of complex sugars for the development of improved versions of existing drugs, the development of novel drugs and the discovery of new biological processes. Momenta is also utilizing its ability to sequence sugars to create technology-enabled generic versions of sugar-based and complex drug products. The Company’s most advanced product candidate is M-Enoxaparin, a technology-enabled generic version of Lovenox®. Based on its understanding of complex sugars, Momenta has created a diversified pipeline of near-term product opportunities, novel development products and discovery candidates. Momenta was founded in 2001 and is headquartered in Cambridge, MA.

Our logo, trademarks, and service marks are the property of Momenta Pharmaceuticals, Inc. All other trade names, trademarks, or service marks are property of their respective owners.

To receive additional information about Momenta, please visit the website at www.momentapharma.com, which does not form a part of this press release.

Contact:
Michael A. Lawless
Momenta Pharmaceuticals, Inc.
617-395-5189

Press Contact
press@momentapharma.com

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