VERTEX PHARMACEUTICALS INCORPORATED
130 WAVERLY STREET • CAMBRIDGE, MA 02139-4242
TEL. 617.444.6100 • FAX 617.444-6483
http://www.vrtx.com

Delivered by FedEx and EDGAR

December 10, 2004

United States Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549
Attn:   Sonia Barros, Esq.
Division of Corporation Finance

Ladies and Gentlemen:

        This letter is intended to provide responses to comments from the staff of the Securities and Exchange Commission (the "Staff") to Vertex Pharmaceuticals Incorporated (the "Registrant") set forth in the Staff's letter to the Registrant, dated November 9, 2004 (the "Comment Letter"), regarding the Registrant's Registration Statement on Form S-3, as originally filed with the Securities and Exchange Commission on October 28, 2004 (the "Registration Statement"), and the prospectus included therein (the "Prospectus").

        The relevant text of the Comment Letter is reproduced below together with the Registrant's response thereto, including text that the Registrant proposes to add to the Prospectus in response to the Staff's comments. If the Staff does not object to the Registrant's proposed responses, the Registrant will file an amendment to the Registration Statement incorporating these changes as well as certain other updates to the Prospectus.

Comment 1.

Response 1.

        The 53/4% Convertible Senior Subordinated Notes due 2011 (the "New Notes") were issued by the Registrant in an exchange offer (the "Exchange") to holders of the Registrant's 5% Subordinated Convertible Notes due 2007 (the "2007 Notes"). The Exchange was completed on September 17, 2004. Consistent with the terms of the Exchange, UBS Securities LLC ("UBS") received a New Note in exchange for 2007 Notes that it held (which had been previously purchased by UBS through the PORTAL market). UBS is a registered broker-dealer and UBS was engaged to act as a dealer-manager in connection with the Exchange and was paid cash for those services.

        The securities held by UBS that are to be registered by the Registration Statement were not issued or sold as underwriting compensation.



        In response to Comment 1, the Registrant proposes to add a new footnote (2) to the entry regarding UBS Securities LLC in the selling securityholder table set forth on page 38 of the Prospectus. The text of the proposed footnote would state:

        Furthermore, the Registrant proposes to amend the seventh paragraph under the section titled "Plan of Distribution" to state:

Comment 2.

Response 2.

        The Registrant confirms that it will file post-effective amendments to the Registration Statement to identify additional selling securityholders as their identities become known to the Registrant, to the extent so required by the rules of the Securities and Exchange Commission. In response to Comment 2, the Registrant proposes to amend the ninth paragraph under the section titled "Plan of Distribution" to state:

Comment 3.

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Response 3.

        The Registrant notes the Staff's comment with respect to the use of Rule 424(b)(5) prospectuses and post-effective amendments and will comply with those requirements.

        The Registrant proposes to amend the indicated text on page 38 of the Prospectus to state:

* * *

        Please contact the undersigned in the event that you have any questions or concerns with respect to this matter. The undersigned can be reached at 617-444-6417. In the event that the undersigned is not available, please contact my colleague, Jeffrey Donohue, at 617-444-6131.

    Very truly yours,

 

 

/s/  
KENNETH S. BOGER      
    Kenneth S. Boger
Senior Vice President and General Counsel

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