1 EXHIBIT 23.3 February 12, 1996 Genome Therapeutics Corp. 100 Beaver Street Waltham, Massachusetts 02154 Re: Genome Therapeutics Corp. Registration Statement on Form S-3 Dear Sirs: We hereby consent to the use of our name under the caption "Experts" in Genome Therapeutics Corp.'s Registration Statement on Form S-3 and in the related prospectus. Very truly yours, /s/ Lahive & Cockfield ................................... Lahive & Cockfield