Exhibit 99

May 15, 2000
Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549

Commissioners:

We are aware that our report dated April 28, 2000 on our review of interim
financial information of Vertex Pharmaceuticals Incorporated (the "Company") for
the period ended March 31, 2000 and included in the Company's quarterly report
on Form 10-Q for the quarter then ended is incorporated by reference in its
registration statements on Form S-8 (File Nos. 33-48030, 33-48348, 33-65742,
33-93224, 33-12325, 333-27011, 333-56179 and 333-79549). Pursuant to Rule 436(c)
under the Securities Act of 1933, this report should not be considered a part of
the registration statement prepared or certified by us within the meaning of
Sections 7 and 11 of that Act.

Yours very truly,

PricewaterhouseCoopers LLP

Boston, MA