Mail Stop 0309 November 9, 2004 Mr. Joshua S. Boger Chief Executive Officer Vertex Pharmaceuticals Incorporated 130 Waverly Street Cambridge, Massachusetts 02139-4242 Re: Vertex Pharmaceuticals Incorporated Registration Statement on Form S-3 filed October 28, 2004 File No. 333-120055 Dear Mr. Boger: We have limited our review of the above referenced filing to only the matters addressed herein. Please understand that the purpose of our review process is to assist you in your compliance with the applicable disclosure requirements and to enhance the overall disclosure in your filing. We look forward to working with you in these respects. We welcome any questions you may have about our comments or on any other aspect of our review. Feel free to call us at the telephone numbers listed at the end of this letter. 1. Please tell us whether UBS Securities LLC is a broker-dealer or an affiliate of a broker-dealer. If UBS Securities LLC is a broker- dealer or affiliate of a broker-dealer, tell us supplementally whether they received these shares as underwriting compensation. We may have additional comments. Please be advised that we consider the resale of securities by broker-dealers to be an indirect primary offering. In that regard, the prospectus must state that such broker-dealer is an underwriter. 2. Please confirm to us and also revise your disclosure to state that you will file a post-effective amendment to identify any additional selling securityholders. 3. Please note that in order to substitute new names for the names of selling securityholders identified in an effective registration statement you can file a Rule 424(b) prospectus only if the change is not material, the number of securities or dollar amount registered does not change, and the new owners` securities can be traced to those covered by the original registration statement. A change that does not meet these requirements must be made by a post-effective amendment. In addition, you must either file a prospectus supplement or a post-effective amendment, as applicable, to substitute new names except for certain donees in the circumstances described in our telephone interpretation H.3 (see 1997 manual of telephone interpretations). Please confirm to us that you will comply with these requirements. In addition, in that regard we refer to your statement on page 38 that, "Selling holders, including their transferees, pledgees or their successors, may from time to time offer and sell any or all of the notes and the common stock into which the notes are convertible pursuant to this prospectus." Please revise your disclosure to indicate that you may need to amend this registration statement to substitute new names. We urge all persons who are responsible for the accuracy and adequacy of the disclosure in the filings reviewed by the staff to be certain that they have provided all information investors require for an informed decision. Since the company and its management are in possession of all facts relating to a company`s disclosure, they are responsible for the accuracy and adequacy of the disclosures they have made. Notwithstanding our comments, in the event the company requests acceleration of the effective date of the pending registration statement, it should furnish a letter, at the time of such request, acknowledging that: ? should the Commission or the staff, acting pursuant to delegated authority, declare the filing effective, it does not foreclose the Commission from taking any action with respect to the filing; ? the action of the Commission or the staff, acting pursuant to delegated authority, in declaring the filing effective, does not relieve the company from its full responsibility for the adequacy and accuracy of the disclosure in the filing; and ? the company may not assert this action as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States. In addition, please be advised that the Division of Enforcement has access to all information you provide to the staff of the Division of Corporation Finance in connection with our review of your filing or in response to our comments on your filing. We will consider a written request for acceleration of the effective date of the registration statement as a confirmation of the fact that those requesting acceleration are aware of their respective responsibilities under the Securities Act of 1933 and the Securities Exchange Act of 1934 as they relate to the proposed public offering of the securities specified in the above registration statement. We will act on the request and, pursuant to delegated authority, grant acceleration of the effective date. We direct your attention to Rules 460 and 461 regarding requesting acceleration of a registration statement. Please allow adequate time after the filing of any amendment for further review before submitting a request for acceleration. Please provide this request at least two business days in advance of the requested effective date. Please direct any questions to Sonia Barros at (202) 824-5304 or Suzanne Hayes at (202) 942-1789. Sincerely, Jeffrey Riedler Assistant Director cc: Michael L. Fantozzi, Esq. Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, PC One Financial Center Boston, MA 02111 Mr. Joshua S. Boger November 9, 2004 Page 1