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  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt">As filed with the Securities and Exchange Commission on June&nbsp;8, 2007
  </DIV>
  
  
  <DIV align="right" style="font-size: 10pt; margin-top: 3pt">Registration No.&nbsp;333-_____
  </DIV>
  
  
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  <DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>UNITED STATES<BR>
  SECURITIES AND EXCHANGE COMMISSION</B>
  </DIV>
  
  <DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
  </DIV>
  
  <DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>FORM S-8</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>REGISTRATION STATEMENT UNDER<BR>
  THE SECURITIES ACT OF 1933</B>
  </DIV>
  
  <DIV align="center" style="font-size: 24pt; margin-top: 12pt"><B>IDENIX PHARMACEUTICALS, INC.</B>
  </DIV>
  
  <DIV align="center" style="font-size: 10pt">(Exact Name of Registrant as Specified in Its Charter)</DIV>
  
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
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      <TD width="47%">&nbsp;</TD>
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      <TD width="47%">&nbsp;</TD>
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  <TR valign="bottom">
      <TD align="center" valign="top"><B>Delaware</B><BR>
  (State or Other Jurisdiction of Incorporation or <BR>
  Organization)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>45-0478605</B><BR>
  (I.R.S. Employer<BR>
  Identification No.)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="47%">&nbsp;</TD>
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      <TD width="47%">&nbsp;</TD>
  </TR>
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  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="center" valign="top"><B>60 Hampshire Street <BR>
  Cambridge, MA</B><BR>
  (Address of Principal Executive Offices)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B><br>02139</B><BR>
  (Zip Code)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>2005 Stock Incentive Plan, as amended</B><BR>
  (Full Title of the Plan)
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>Jean-Pierre Sommadossi<BR>
  President and Chief Executive Officer<BR>
  Idenix Pharmaceuticals, Inc.<BR>
  60 Hampshire Street<BR>
  Cambridge, MA 02139</B><BR>
  (Name and Address of Agent For Service)<BR>
  <B>617-995-9800</B><BR>
  (Telephone Number, Including Area Code, of Agent For Service)
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>CALCULATION OF REGISTRATION FEE</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
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      <TD width="1%">&nbsp;</TD>
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      <TD width="1%">&nbsp;</TD>
  </TR><TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="21" style="border-bottom: 3px double #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD>&nbsp;</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Proposed Maximum</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Proposed Maximum</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="center">Title of Securities</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Amount to be</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Offering Price Per</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Aggregate Offering</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Amount of</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="center">to be Registered</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Registered(1)</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Share</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Price</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Registration Fee</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  
  <!-- End Table Head -->
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      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
                      <TD valign="top" style="border-top: 1px solid #000000"><DIV style="margin-left:0px; text-indent:-0px">Common Stock, $0.001 par value
  per share
  </DIV></TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD align="left" valign="top" style="border-top: 1px solid #000000">3,700,000&nbsp;shares
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD nowrap align="right" valign="top" style="border-top: 1px solid #000000">$</TD>
      <TD align="right" valign="top" style="border-top: 1px solid #000000">7.12</TD>
      <TD nowrap valign="top" style="border-top: 1px solid #000000">(2)</TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD nowrap align="right" valign="top" style="border-top: 1px solid #000000">$</TD>
      <TD align="right" valign="top" style="border-top: 1px solid #000000">26,344,000</TD>
      <TD nowrap valign="top" style="border-top: 1px solid #000000">(2)</TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD nowrap align="right" valign="top" style="border-top: 1px solid #000000">$</TD>
      <TD align="right" valign="top" style="border-top: 1px solid #000000">809</TD>
      <TD nowrap valign="top" style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="21" style="border-top: 3px double #000000">&nbsp;</TD>
  </TR>
  
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>In accordance with Rule&nbsp;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.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>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&#146;s Common Stock as reported on the NASDAQ Global Market on
  June&nbsp;7, 2007.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  
  <P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
  </DIV>
  
  <!-- PAGEBREAK -->
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  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  
  
  
  
  
  
  <!-- TOC -->
  <A name="toc"><DIV align="CENTER" style="page-break-before:always"><U><B>TABLE OF CONTENTS</B></U></DIV></A>
  
  <P><CENTER>
  <TABLE border="0" width="90%" cellpadding="0" cellspacing="0">
  <TR>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
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  	<TD width="3%"></TD>
  	<TD width="76%"></TD>
  </TR>
  <TR><TD colspan="9"><A HREF="#000">STATEMENT OF INCORPORATION BY REFERENCE</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#001">Item&nbsp;5.&nbsp;&nbsp; Interests of Named Experts and Counsel.</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#002">Item&nbsp;8.&nbsp;&nbsp; Exhibits.</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#003">SIGNATURES</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#004">INDEX TO EXHIBITS</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b65700s8exv4w2.htm">Ex-4.2 Certificate of Amendment of Restated Certificate of Incorporation</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b65700s8exv5w1.htm">Ex-5.1 Opinion of Wilmer Cutler Pickering Hale and Dorr LLP</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b65700s8exv23w2.htm">Ex-23.2 Consent of PricewaterhouseCoopers LLP</A></TD></TR>
  </TABLE>
  </CENTER>
  <!-- /TOC -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  
  
  
  
  
  
  
  <!-- link1 "STATEMENT OF INCORPORATION BY REFERENCE" -->
  <DIV align="left"><A NAME="000"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>STATEMENT OF INCORPORATION BY REFERENCE</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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&#146;s common stock, $0.001 par value per share, to be
  issued under the registrant&#146;s 2005 Stock Incentive Plan, as amended.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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.&nbsp;333-128882) on October&nbsp;7, 2005 relating to 2,300,000 shares of common stock to
  be offered and sold under the registrant&#146;s 2005 Stock Incentive Plan, as amended.
  </DIV>
  <!-- link2 "Item&nbsp;5.&nbsp;&nbsp; Interests of Named Experts and Counsel." -->
  <DIV align="left"><A NAME="001"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Item&nbsp;5.&nbsp;&nbsp; Interests of Named Experts and Counsel.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Wilmer Cutler Pickering Hale and Dorr LLP (&#147;WilmerHale&#148;) 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&nbsp;shares of the registrant&#146;s common stock.
  </DIV>
  <!-- link2 "Item&nbsp;8.&nbsp;&nbsp; Exhibits." -->
  <DIV align="left"><A NAME="002"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B>Item&nbsp;8.&nbsp;&nbsp; Exhibits.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Exhibit&nbsp;Index immediately preceding the exhibits is incorporated herein by reference.
  </DIV>
  
  <P align="center" style="font-size: 10pt"><!-- Folio -->-1-<!-- /Folio -->
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  <!-- link1 "SIGNATURES" -->
  <DIV align="left"><A NAME="003"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>SIGNATURES</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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<SUP style="font-size: 85%; vertical-align: text-top">th</SUP> day of June, 2007.
  </DIV>
  
  <TABLE width="100%" border="0" cellspacing="0" cellpadding="0" style="font-size: 10pt">
  <TR>
      <TD width="48%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="35%">&nbsp;</TD>
      <TD width="15%">&nbsp;</TD>
  </TR>
  <TR>
      <TD valign="top" align="left">&nbsp;</TD>
      <TD colspan="3" align="left">IDENIX PHARMACEUTICALS, INC.<BR>
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD valign="top">By:&nbsp;&nbsp;</TD>
      <TD colspan="2" style="border-bottom: 1px solid #000000" align="left">/s/ Jean Pierre Sommadossi
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">Jean-Pierre Sommadossi&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">President and Chief Executive Officer&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR>
  <TR>
      <TD colspan="5">&nbsp;</TD>
  </TR>
  </TABLE>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>POWER OF ATTORNEY AND SIGNATURES</B>
  </DIV>
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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.
  </DIV>
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="40%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="20%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><u><B>Signature</B></u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><u><B>Title</B></u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><u><B>Date</B></u></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Jean-Pierre Sommadossi
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Jean-Pierre Sommadossi
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">President and Chief
  Executive Officer and
  Director (Principal
  executive officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ David Blanchard
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  David Blanchard
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Interim Chief Financial
  Officer (Principal
  financial and
  accounting officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Charles W. Cramb
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Charles W. Cramb
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Thomas Ebeling
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Thomas Ebeling
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;5, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Wayne T. Hockmeyer
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Wayne T. Hockmeyer
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;8, 2007</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt"><!-- Folio -->-2-<!-- /Folio -->
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="40%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="20%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Thomas Hodgson
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Thomas R. Hodgson
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Norman C. Payson
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Norman C. Payson
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;5, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Robert E. Pelzer
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Robert E. Pelzer
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;5, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Denise Pollard-Knight
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Denise Pollard-Knight
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Pamela Thomas-Graham
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  Pamela Thomas-Graham
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">June&nbsp;4, 2007</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt"><!-- Folio -->-3-<!-- /Folio -->
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <!-- link1 "INDEX TO EXHIBITS" -->
  <DIV align="left"><A NAME="004"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>INDEX TO EXHIBITS</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="87%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px"><u>Number</u>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top"><u>Description</u></TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.1(1)
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Restated Certificate of Incorporation of the Registrant, as amended</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate of Amendment of Restated Certificate of Incorporation</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.3(2)
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated By-Laws of the Registrant</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">5.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Opinion of Wilmer Cutler Pickering Hale and Dorr LLP, counsel to
  the Registrant</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Wilmer Cutler Pickering Hale and Dorr LLP
  (included in Exhibit&nbsp;5)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of PricewaterhouseCoopers LLP, independent registered
  public accounting firm</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">24.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Power of attorney (included on the signature pages of this
  registration statement)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  
  <DIV align="left">
  <DIV style="font-size: 3pt; margin-top: 36pt; width: 18%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  <TR>
      <TD width="3%"></TD>
      <TD width="1%"></TD>
      <TD width="96"></TD>
  </TR>
  
  <TR valign="top">
      <TD nowrap align="left">(1)</TD>
      <TD>&nbsp;</TD>
      <TD>Previously filed with the Securities and Exchange Commission as an Exhibit to the
  Registrant&#146;s Registration Statement on Form S-1, as amended (File No.&nbsp;333-111157); Form 10-Q
  for the quarterly period ended June&nbsp;30, 2004 (File No.&nbsp;000-49839); and Form 10-K for the year
  ended December&nbsp;31, 2005 (File No.&nbsp;000-49839) and incorporated herein by reference.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
  <TR valign="top">
      <TD nowrap align="left">(2)</TD>
      <TD>&nbsp;</TD>
      <TD>Previously filed with the Securities and Exchange Commission as an Exhibit to the
  Registrant&#146;s Form 10-Q for the quarterly period ended June&nbsp;30, 2004 (File No.&nbsp;000-49839) and
  incorporated herein by reference.</TD>
  </TR>
  
  </TABLE>
  
  
  
  
  <P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
  </DIV>
  
  </BODY>
  </HTML>
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metadata_filer: {"company-data": {"conformed-name": "IDENIX PHARMACEUTICALS INC", "cik": "0001093649", "assigned-sic": "2834", "irs-number": "450478605"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-143620", "film-number": "07910292"}, "business-address": {"street1": "60 HAMPSHIRE STREET", "street2": ".", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "(617) 250-3100"}, "mail-address": {"street1": "60 HAMPSHIRE STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}, "former-company": {"former-conformed-name": "NOVIRIO PHARMACEUTICALS LTD", "date-changed": "19990820"}}
text: sv8
  Table of Contents
  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
  Table of Contents
  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.
  -1-
  Table of Contents
  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
  -2-
  Table of Contents
  /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
  -3-
  Table of Contents
  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.