FOURTHAMENDMENT

Exhibit 10.11

FOURTH AMENDMENT

This Fourth Amendment, effective as of the date set forth above the signatures of the parties below, pertains to the Exclusive Patent License Agreement (“Agreement ###-###-####”), effective on October 31, 2002, as subsequently amended by a First Amendment on November 15, 2002, a Second Amendment on July 17, 2004, and a Third Amendment on August 5, 2006, by and between the Massachusetts Institute of Technology (“M.I.T.”) and Momenta Pharmaceuticals, Inc. (“COMPANY”).

WHEREAS, COMPANY no longer plans to commercialize the technology included in MIT Case Number 9085, “Aerosol Administration of Heparin to the Lungs,” by Dongfang Liu, Yiwei Qi, Ram Sasisekharan, Mallikarjun Sundaram and Ganesh Venkataraman;

WHEREAS, M.I.T. agrees to remove this case from Agreement ###-###-#### without penalty to COMPANY;

NOW, THEREFORE, M.I.T. and COMPANY hereby agree to remove this case and all future obligations relating to this case from Agreement ###-###-####.

All other terms and conditions of Agreement ###-###-#### shall remain unchanged.

The AMENDMENT EFFECTIVE DATE is January 10, 2007.

Agreed to for: