Investor FAQ

Q.	Where is Idenix incorporated?
A.	Idenix Pharmaceuticals is incorporated in Delaware.

Q.	Where is the Idenix headquarters located?
A.	Idenix headquarters is located at 60 Hampshire Street, Cambridge, Massachusetts, 02139.

Q.	Who is Idenix's outside legal counsel?
A.	Wilmer Cutler Pickering Hale and Dorr LLP 60 State Street Boston, Massachusetts 02109 Phone: (617) 526-6000 Fax: (617) 526-5000

Q.	Who are Idenix’s independent accountants?
A.	PricewaterhouseCoopers, LLP One International Place Boston, MA 02110 United States of America Telephone: (617) 530 5000 Telecopier: (617) 530 5001

Q.	What is Idenix Pharmaceuticals’ fiscal year-end?
A.	Our fiscal year-end is December 31st. Reporting quarters correspond with calendar quarters.

When did Idenix become a publicly traded company? At what price? How many shares were issued in the IPO?

Idenix’s common stock began trading on July 22, 2004. The pricing of its initial public offering of 5.8 million shares of common stock was $14.00 per share. Idenix offered 4.6 million shares and certain selling stockholders of Idenix offered 1.2 million shares. Concurrent with the initial public offering, Idenix also agreed to a private placement of 5.4 million shares to Novartis at the initial public offering price to be completed concurrently with the consummation of the initial public offering.

Q.	On what exchange is Idenix listed?
A.	Idenix Pharmaceuticals is listed on the Nasdaq Global Market under the ticker symbol IDIX.

Q.	How can I purchase stock directly from the company?
A.	You can purchase Idenix stock through any registered broker. Idenix does not have a Direct Stock Purchase Plan at this time.

Q.	What is your stock’s CUSIP#?
A.	The CUSIP# for the Idenix Common Stock is 45166R 20 4.

Q.	Who is Idenix’s Transfer Agent?
A.	The transfer agent for Idenix Pharmaceuticals is Computershare Trust Company. For shareholder inquiries, please contact Shareholder Relations at the following address: Computershare Trust Company, N.A. 250 Royall St. Canton, MA 02021 781-575-3400

Q.	I’ve lost my stock certificates. How can I replace them?
A.	Contact Computershare Trust Company, N.A. who can look up your records and make any necessary adjustments. There may be a fee involved for replacing lost stock certificates.

Q.	How can I be alerted to the latest news about Idenix Pharmaceuticals?
A.	Please sign up for our E-mail Alerts for the most current investor and company news from Idenix or e-mail us your contact information at investor@idenix.com.