S-8

As filed with the Securities and Exchange Commission on June 8, 2007

Registration No. 333-_____

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT UNDER
THE SECURITIES ACT OF 1933

IDENIX PHARMACEUTICALS, INC.

(Exact Name of Registrant as Specified in Its Charter)

Delaware
(State or Other Jurisdiction of Incorporation or
Organization) 45-0478605
(I.R.S. Employer
Identification No.)

60 Hampshire Street
Cambridge, MA
(Address of Principal Executive Offices)
02139
(Zip Code)

2005 Stock Incentive Plan, as amended
(Full Title of the Plan)

Jean-Pierre Sommadossi
President and Chief Executive Officer
Idenix Pharmaceuticals, Inc.
60 Hampshire Street
Cambridge, MA 02139
(Name and Address of Agent For Service)
617-995-9800
(Telephone Number, Including Area Code, of Agent For Service)

CALCULATION OF REGISTRATION FEE

		Proposed Maximum			Proposed Maximum
Title of Securities	Amount to be	Offering Price Per			Aggregate Offering			Amount of
to be Registered	Registered(1)	Share			Price			Registration Fee
Common Stock, $0.001 par value per share	3,700,000 shares	$	7.12	(2)	$	26,344,000	(2)	$	809

(1) In accordance with Rule 416 under the Securities Act of 1933, as amended, this registration statement shall be deemed to cover any additional securities that may from time to time be offered or issued to prevent dilution resulting from stock splits, stock dividends or similar transactions.

(2) Estimated solely for the purpose of calculating the registration fee pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as amended, and based upon the average of the high and low prices of the Registrant’s Common Stock as reported on the NASDAQ Global Market on June 7, 2007.

TABLE OF CONTENTS

STATEMENT OF INCORPORATION BY REFERENCE
	Item 5.   Interests of Named Experts and Counsel.
	Item 8.   Exhibits.
SIGNATURES
INDEX TO EXHIBITS
Ex-4.2 Certificate of Amendment of Restated Certificate of Incorporation
Ex-5.1 Opinion of Wilmer Cutler Pickering Hale and Dorr LLP
Ex-23.2 Consent of PricewaterhouseCoopers LLP

STATEMENT OF INCORPORATION BY REFERENCE

     This registration statement on Form S-8 is filed to register the offer and sale of an additional 3,700,000 shares of the registrant’s common stock, $0.001 par value per share, to be issued under the registrant’s 2005 Stock Incentive Plan, as amended.

     This registration statement incorporates by reference the contents of the registration statement on Form S-8 previously filed by the registrant with the Securities and Exchange Commission (File No. 333-128882) on October 7, 2005 relating to 2,300,000 shares of common stock to be offered and sold under the registrant’s 2005 Stock Incentive Plan, as amended.

     Item 5.   Interests of Named Experts and Counsel.

     Wilmer Cutler Pickering Hale and Dorr LLP (“WilmerHale”) has opined as to the legality of the securities being offered by this registration statement. Attorneys at WilmerHale beneficially own, in the aggregate, 59,843 shares of the registrant’s common stock.

     Item 8.   Exhibits.

     The Exhibit Index immediately preceding the exhibits is incorporated herein by reference.

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SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Cambridge, Massachusetts, on this 8^th day of June, 2007.

IDENIX PHARMACEUTICALS, INC.
By:	/s/ Jean Pierre Sommadossi
	Jean-Pierre Sommadossi
	President and Chief Executive Officer

POWER OF ATTORNEY AND SIGNATURES

     We, the undersigned officers and directors of Idenix Pharmaceuticals, Inc., hereby severally constitute and appoint Jean-Pierre Sommadossi, John F. Weidenbruch and Maria D. Stahl and each of them singly, our true and lawful attorneys with full power to them, and each of them singly, to sign for us and in our names in the capacities indicated below, the registration statement on Form S-8 filed herewith and any and all subsequent amendments to said registration statement, and generally to do all such things in our names and on our behalf in our capacities as officers and directors to enable Idenix Pharmaceuticals, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming our signatures as they may be signed by our said attorneys, or any of them, to said registration statement and any and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Jean-Pierre Sommadossi Jean-Pierre Sommadossi	President and Chief Executive Officer and Director (Principal executive officer)	June 4, 2007
/s/ David Blanchard David Blanchard	Interim Chief Financial Officer (Principal financial and accounting officer)	June 4, 2007
/s/ Charles W. Cramb Charles W. Cramb	Director	June 4, 2007
/s/ Thomas Ebeling Thomas Ebeling	Director	June 5, 2007
/s/ Wayne T. Hockmeyer Wayne T. Hockmeyer	Director	June 8, 2007

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/s/ Thomas Hodgson Thomas R. Hodgson	Director	June 4, 2007
/s/ Norman C. Payson Norman C. Payson	Director	June 5, 2007
/s/ Robert E. Pelzer Robert E. Pelzer	Director	June 5, 2007
/s/ Denise Pollard-Knight Denise Pollard-Knight	Director	June 4, 2007
/s/ Pamela Thomas-Graham Pamela Thomas-Graham	Director	June 4, 2007

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INDEX TO EXHIBITS

Number	Description
4.1(1)	Restated Certificate of Incorporation of the Registrant, as amended
4.2	Certificate of Amendment of Restated Certificate of Incorporation
4.3(2)	Amended and Restated By-Laws of the Registrant
5.1	Opinion of Wilmer Cutler Pickering Hale and Dorr LLP, counsel to the Registrant
23.1	Consent of Wilmer Cutler Pickering Hale and Dorr LLP (included in Exhibit 5)
23.2	Consent of PricewaterhouseCoopers LLP, independent registered public accounting firm
24.1	Power of attorney (included on the signature pages of this registration statement)

(1)	Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant’s Registration Statement on Form S-1, as amended (File No. 333-111157); Form 10-Q for the quarterly period ended June 30, 2004 (File No. 000-49839); and Form 10-K for the year ended December 31, 2005 (File No. 000-49839) and incorporated herein by reference.
(2)	Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant’s Form 10-Q for the quarterly period ended June 30, 2004 (File No. 000-49839) and incorporated herein by reference.

EX-4.2

CERTIFICATE OF AMENDMENT
OF
RESTATED CERTIFICATE OF INCORPORATION
OF
IDENIX PHARMACEUTICALS, INC.

     Idenix Pharmaceuticals, Inc. (the “Corporation”), organized and existing under and by virtue of the General Corporation Law of the State of Delaware, does hereby certify as follows:

     The Board of Directors of the Corporation duly adopted at a meeting duly called, pursuant to Section 242 of the General Corporation Law of the State of Delaware, resolutions setting forth an amendment to the Restated Certificate of Incorporation of the Corporation, as amended, and declaring said amendment to be advisable. The stockholders of the Corporation duly approved said proposed amendment the Corporation’s 2007 annual meeting of stockholders in accordance with Sections 242 of the General Corporation Law of the State of Delaware. The resolutions setting forth the amendment are as follows:

RESOLVED:	That the first sentence of Article Fourth of the Restated Certificate of Incorporation of the Corporation be and hereby is deleted in its entirety and the following new first sentence of Article Fourth be inserted in lieu thereof:
	“FOURTH: The total number of shares of all classes of stock which the Corporation shall have authority to issue is 125,000,000 shares of Common Stock, $.001 par value per share (“Common Stock”).”

     IN WITNESS WHEREOF, the Corporation has caused this Certificate of Amendment to be signed by its Chairman, Chief Executive Officer and President this 1^st day of June, 2007.

IDENIX PHARMACEUTICALS, INC.
By:	/s/ Jean-Pierre Sommadossi
	Jean-Pierre Sommadossi
	Chairman, Chief Executive Officer and President

EX-5.1

Exhibit 5.1

June 8, 2007
Idenix Pharmaceuticals, Inc. 60 Hampshire Street Cambridge, MA 02139

Re:   Idenix Pharmaceuticals, Inc. 2005 Stock Incentive Plan, as amended

Ladies and Gentlemen:

     We have assisted in the preparation of a Registration Statement on Form S-8 (the “Registration Statement”) to be filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), relating to an aggregate of 3,700,000 shares of common stock, $0.001 par value per share (the “Shares”), of Idenix Pharmaceuticals, Inc., a Delaware corporation (the “Company”), issuable under the Company’s 2005 Stock Incentive Plan, as amended (the “Plan”).

     We have examined the Restated Certificate of Incorporation, as amended and the Amended and Restated By-Laws of the Company, each as amended and restated to date, and originals, or copies certified to our satisfaction, of all pertinent records of the meetings of the directors and stockholders of the Company, the Registration Statement and such other documents relating to the Company as we have deemed material for the purposes of this opinion.

     In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, photostatic or other copies, the authenticity of the originals of any such documents and the legal competence of all signatories to such documents.

     We assume that the appropriate action will be taken, prior to the offer and sale of the Shares in accordance with the Plan, to register and qualify the Shares for sale under all applicable state securities or “blue sky” laws.

     We express no opinion herein as to the laws of any state or jurisdiction other than the state laws of The Commonwealth of Massachusetts, the General Corporation Law of the State of Delaware and the federal laws of the United States of America.

     It is understood that this opinion is to be used only in connection with the offer and sale of the Shares while the Registration Statement is in effect.

     Please note that we are opining only as to the matters expressly set forth herein, and no opinion should be inferred as to any other matters.

Idenix Pharmaceuticals, Inc.
June 8, 2007
Page 2

     Based on the foregoing, we are of the opinion that the Shares have been duly authorized for issuance and, when the Shares are issued and paid for in accordance with the terms and conditions of the Plan, the Shares will be validly issued, fully paid and nonassessable.

     We hereby consent to the filing of this opinion with the Commission in connection with the Registration Statement in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act. In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission.

Very Truly Yours,

WILMER CUTLER PICKERING
HALE AND DORR LLP

By:	/s/ Susan W. Murley
	Susan W. Murley, Partner

EX-23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our report dated March 14, 2007 relating to the financial statements, management’s assessment of the effectiveness of internal control over financial reporting and the effectiveness of internal control over financial reporting, which appears in Idenix Pharmaceuticals, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2006.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts
June 8, 2007