— Extends Product Applications of Its Characterization Technology Beyond Heparins

CAMBRIDGE, MA — January 13, 2005 – Momenta Pharmaceuticals, Inc. (Nasdaq: MNTA), a biotechnology company developing drugs based on sugar sequencing technology, today announced its goals relating to the application of its proprietary technology to therapeutic protein drugs containing sugars. Momenta’s goals for its glycoprotein program in 2005 are to characterize the sugars on multiple glycoprotein drugs and to establish a glycoprotein product partnership.

“We believe that we have an opportunity to take our proprietary capability to characterize complex sugars and apply it to the sizeable market of glycoproteins,” said Alan Crane, Chairman and CEO of Momenta. The global market for therapeutic proteins exceeded $33 billion in 2003. Given that most of the leading marketed therapeutic proteins and antibodies are glycosylated, or coated with complex sugars, Momenta believes there is a substantial opportunity for its characterization technology to be applied to analyze major marketed products. To date, it has not been possible to thoroughly characterize the sugars on glycoproteins due to lack of available technology. Glycosylation determines critical product properties, including efficacy, safety, specificity, half-life, and immunogenicity.

Momenta’s characterization capabilities for glycoproteins can be applied to pursue multiple product and partnering opportunities, including enabling characterization-based life cycle management by better understanding existing marketed products, facilitating follow-on or generic versions of glycoproteins, or creating improved versions of glycoproteins through rational engineering.

“We believe that the application of our characterization technology to glycoproteins significantly broadens our product opportunities and will effectively complement our existing portfolio of heparin-based products such as M-Enoxaparin, M-Dalteparin, and M118,” concluded Mr. Crane.

About Momenta
Momenta Pharmaceuticals, Inc. is a biotechnology company specializing in the sequencing and engineering 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 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 novel discovery and development candidates. Momenta was founded in 2001 and is headquartered in Cambridge, MA.

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

Forward Looking Statements
Statements in this press release regarding Momenta Pharmaceuticals Inc.’s future expectations, beliefs, goals, plans or prospects (including Momenta’s plans to characterize the sugars on multiple glycoproteins and establish a product partnership in 2005) constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Momenta’s actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including those factors contained in Momenta’s final prospectus dated June 21, 2004 filed with the Securities and Exchange Commission in connection with Momenta’s initial public offering under the section “Risk Factors,” as well as other documents that may be filed by Momenta from time to time with the Securities and Exchange Commission. Forward-looking statements include statements regarding Momenta’s expectations, beliefs, intentions or strategies regarding the future and can be identified by forward-looking words such as “anticipate”, “believe”, “could”, “estimate”, “expect”, “intend”, “may”, “should”, “will”, and “would” or similar words. Momenta assumes no obligations to update the information included in this press release.
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 and are not the property of Momenta Pharmaceuticals, Inc.

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

Press Contact
press@momentapharma.com

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