Document:

<PAGE>

                                                                    Exhibit 10.2

          Confidential Materials omitted and filed separately with the

         Securities and Exchange Commission. Asterisks denote omissions.

                               PACKAGING AGREEMENT

          This Packaging Agreement (this "Packaging Agreement"), dated June 22,
2006 (the "Effective Date"), by and between Idenix Pharmaceuticals, Inc., a
Delaware corporation ("Idenix"), and Novartis Pharmaceuticals Corporation, a
Delaware corporation ("NPC").

                                   WITNESSETH:

          WHEREAS, Idenix desires to engage NPC to Package the Product upon the
terms and subject to the conditions set forth herein; and

          WHEREAS, NPC wishes to Package the Product upon the terms and subject
to the conditions set forth herein; and

          NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein and for other good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

          1.1. Definitions.

          As used in this Packaging Agreement, the following terms will have the
meanings ascribed to them below:

          (a) "AAA" has the meaning set forth in Section 12.12.(b)(i) of this
Packaging Agreement.

          (b) "Accounting Standards" with respect to NPC means generally
accepted accounting principles in the United States or International Accounting
Standards.

          (c) "Affiliate" means any corporation, company, partnership, joint
venture and/or firm which controls or is controlled by or is under common
control with a Party to this Packaging Agreement. For purposes of this
definition, "control" or "controlled" means (a) in the case of corporate
entities, direct or indirect ownership of at least fifty percent (50%) of the
stock or shares having the right to vote for the election of directors, and (b)
in the case of non-corporate entities, direct or indirect ownership of at least
fifty percent (50%) of the equity interest with the power to direct the
management and policies of such non-corporate entities. The Parties acknowledge
that in the case of certain entities organized under the laws of certain
countries outside the United States, the maximum percentage ownership permitted
by law for a foreign investor may be less than fifty percent (50%), and that in
such case such lower percentage shall be substituted in the preceding sentence;
provided that such foreign investor has the power to direct the

<PAGE>

management and policies of such entity. Notwithstanding the foregoing, neither
Party shall be considered an Affiliate of the other for purposes of this
Packaging Agreement.

          (d) "Breaching Party" has the meaning set forth in Section 8.3 of this
Packaging Agreement.

          (e) "Bulk Product" means a pharmaceutical preparation in galenical
form containing beta-L-deoxy-thymidine, also known as telbivudine, as the sole
active ingredient.

          (f) "Business Day" means a day on which banking institutions in both
New York, New York and Basel, Switzerland are open for business.

          (g) "C.O.D." means cash on delivery.

          (h) "Commercially Reasonable Efforts" means, with respect to the
efforts to be expended by a Party with respect to any objective, reasonable,
diligent, good faith efforts to accomplish such objective as such Party would
normally use to accomplish a similar objective under similar circumstances.

          (i) "Confidential Information" has the meaning set forth in Section
10.1.

          (j) "Effective Date" means the date written in the preamble of this
Packaging Agreement.

          (k) "Executive Officers" means the Chief Executive Officer of Idenix
(or a senior executive officer of Idenix designated by Idenix' Chief Executive
Officer) and the Chief Executive Officer of NPC (or a senior executive officer
of NPC designated by NPC's Chief Executive Officer).

          (l) "Fee" has the meaning set forth in Section 6.1 of this Packaging
Agreement.

          (m) "Forms" has the meaning set forth in Section 12.7 of this
Packaging Agreement.

          (n) "Fully Allocated Manufacturing Cost" means, with respect to NPC's
activities under this Packaging Agreement, all direct and indirect costs and
overhead allocable to conduct of such activities in accordance with the
Accounting Standards, including but not limited to project and cost accounting
consistently applied, such cost items to include, without limitation, costs of
raw materials, supplies, other resources consumed in the conduct of such
activity, rent, real estate depreciation, utilities, insurance, equipment lease
payments, equipment depreciation and labor, plus general and administrative and
similar expenses reasonably allocated to the conduct of such Packaging
activities. For the avoidance of doubt, to the extent incurred by NPC, Fully

                                        2

<PAGE>

Allocated Manufacturing Cost shall include the expenses for transportation of
the Bulk Product from the point of entry into the United States to the packaging
facility of NPC, including warehousing, customs clearance, transportation,
insurance and quality assurance and shall exclude the cost of Bulk Product.

          (o) "including" or "includes" means "including, without limitation,"
or "includes, without limitation".

          (p) "Indemnified Party" has the meaning set forth in Section 11.3 of
this Packaging Agreement.

          (q) "Indemnifying Party" has the meaning set forth in Section 11.3 of
this Packaging Agreement.

          (r) "Law" means any law, statute, rule, regulation, ordinance or other
pronouncement having the effect of law of any federal, national, multinational,
state, country, city or other political subdivision, or any rule, regulation, or
published guidelines promulgated by any governmental entity, law, statute, rule,
regulation, ordinance or other pronouncement having the effect of law of any
federal, national, state, provincial, county, city or other political
subdivision.

          (s) "Losses" means liabilities, losses, costs, damages, fees or
expenses (including reasonable fees and expenses of legal counsel).

          (t) "Non-Breaching Party" has the meaning set forth in Section 8.3 of
this Packaging Agreement.

          (u) "Packaged Product" means the Bulk Product in final packaged form,
including approved labeling, labeling inserts as required by applicable law,
primary packaging, including but not limited to wholesale bottling, and
secondary packaging, including but not limited to cartoning, packing and other
forms of packaging necessary to meet the legal and commercial requirements for
sale of such product.

          (v) "Packaging" means the process of packaging and labeling the Bulk
Product, thereby creating the Packaged Product. The terms "Package" and
"Packaged" shall be interpreted accordingly.

          (w) "Packaging Agreement" has the meaning set forth in the preamble
hereof.

          (x) "Packaging Materials" means any material employed in the Packaging
of the Bulk Product, excluding freight containers and other outer packaging used
solely for facilitating transportation and shipment, but including the product
label, information leaflet and other product inserts necessary to meet legal
requirements.

                                        3

<PAGE>

          (y) "Party" means each of NPC and Idenix.

          (z) "Proposed Resolution Deadline" has the meaning set forth in
Section 12.12.(b)(iii) of this Packaging Agreement.

          (aa) "Quality Agreement" has the meaning set forth in Section 5.1 of
this Packaging Agreement.

          (bb) "Rejection" has the meaning set forth in Section 3.4(a) of this
Packaging Agreement.

          (cc) "Rejection Disagreement" has the meaning set forth in Section
3.4(b) of this Packaging Agreement.

          (dd) "Term" has the meaning set forth in Section 8.1 of this Packaging
Agreement.

          (ee) "Territory" means the United States of America, and all of its
territories and possessions, and shall include Puerto Rico.

          (ff) "Third Party" means any entity other than NPC or Idenix, or any
of their respective Affiliates.

          (gg) "Third-Party Claim" has the meaning set forth in Section 11.3 of
this Packaging Agreement.

                                    ARTICLE II
                                    PACKAGING

          2.1. Engagement. During the Term and upon the terms and subject to the
conditions set forth herein, Idenix hereby agrees to have NPC Package, and NPC
agrees to Package, all of Idenix' requirements for the Packaged Product for sale
in the Territory.

          2.2. Supply of Bulk Product. With reference to the provisions
regarding the supply of Packaged Product by NPC to Idenix, Idenix will be
responsible for providing to NPC such Bulk Product free of charge in such
quantities as are sufficient for NPC to Package the Bulk Product and meet
Idenix' orders for Packaged Product. Idenix will be responsible for providing
such Bulk Product to NPC no later than [**] months in advance of the delivery
date stated in accordance with Section 3.2.

          2.3. Importation and Delivery of Bulk Product. Idenix will be
responsible for importing Bulk Product into the United States using a customs
broker designated by NPC reasonably acceptable to Idenix. Idenix will further be
responsible for transporting Bulk Product imported into the United States from
the point of entry to

                                        4

<PAGE>

NPC's packaging facility designated in, or in accordance with, Section 2.5
hereto using the carrier or carriers designated by NPC reasonably acceptable to
Idenix and following NPC's standard procedure applicable to this type of
transports. NPC will fully insure or procure the insurance of all consignments
of the Bulk Product between the time of delivery of the Bulk Product to NPC and
NPC's supply of Packaged Product to Idenix, provided, however, that NPC will not
be responsible for loss of or damage to the Bulk Product other than (i) by not
providing aforesaid insurance coverage, (ii) in the event of NPC's breach of
this Packaging Agreement or (iii) NPC's negligence or willful misconduct.

          2.4. Packaging Materials. NPC shall procure all Packaging Materials
for Packaged Product under this Packaging Agreement. All such Packaging
Materials will (i) be in accordance with the Specifications, and (ii) include
the appropriate product trademarks associated with the Packaged Product, in the
manner and to the extent specified in the Specifications. Idenix will be
responsible for ensuring the accuracy of all information contained in the
Specifications and for the compliance of the Specifications and of all such
information with applicable Law. NPC shall use reasonable efforts to accommodate
any changes to the Specifications required by Law and/or reasonably requested by
Idenix, at Idenix' expense, within a reasonable timeframe to be agreed upon by
both Parties.

          2.5. Facility. NPC shall Package the Bulk Product at its facility at
25 Old Mill Road, Suffern, NY 10901. NPC may not change the facility at which it
Packages the Bulk Product without the prior written consent of Idenix.

                                   ARTICLE III
                         FORECASTS, ORDERS AND SHIPMENT

          3.1. Forecasts.

          (a) In order to assist the planning of production runs for the
Packaging of the Bulk Product, Idenix shall, at least [**] days in advance of
the commencement of each calendar month during the Term, provide NPC with its
monthly rolling forecast of the quantities of Packaged Product that Idenix
estimates it will be requiring for the coming [**] months.

          (b) NPC shall be entitled to order sufficient quantities of long lead
time Packaging Materials, but no more than [**] months' demand, to meet Idenix'
forecasts and Idenix shall be responsible for the cost of such Packaging
Materials in the event and to the extent that they are not used because the
forecasted amounts are not ordered in accordance with Section 3.2.

          (c) The forecast for the first [**] months of each rolling forecast
pursuant to Section 3.1(a) shall be binding, thereby committing Idenix to have
NPC Package the

                                        5

<PAGE>

stated amount of Bulk Product by placing corresponding orders in accordance with
Section 3.2 below and committing NPC to package such amount.

          3.2. Orders. Idenix will place orders for Packaged Product in writing
at least [**] weeks in advance of Idenix' requested delivery dates. Each such
order will specifically refer to this Packaging Agreement and will specify the
quantity and description of Packaged Product ordered, the requested delivery
date, the delivery address, the transportation method and carrier and any
special instructions requested, provided, however, that (i) Idenix will not
request more than one (1) delivery per calendar month, (ii) each order will set
forth a delivery date that is not less than [**] complete calendar weeks after
the date of such order, and (iii) and no such delivery date shall be on a day
other than a Business Day. The minimum size of any order placed by Idenix will
be a full batch in accordance with Exhibit 1, except with the advance written
approval of NPC. In addition, with respect to each month covered by such order,
such order will be for amounts of Packaged Product not more than one batch over
or under the forecasted amounts for the Packaged Product for such month
contained in the binding forecast delivered hereunder in accordance with Section
3.1(c). The order forms will be delivered to such location as NPC designates in
writing to Idenix from time to time. The date an order will be deemed placed
will be the date that NPC actually receives the order form containing such
order. Each such order will be a firm order and Idenix will be fully responsible
for any changes to a firm order. NPC in its sole discretion may reject any order
that does not comply with this Packaging Agreement and all other orders that
comply with this Packaging Agreement will be accepted. Orders will be deemed
accepted by NPC unless NPC provides notification of rejection in accordance with
the immediately preceding sentence, along with the reason for rejection, to
Idenix within five (5) Business Days of receipt of the order. In the event that
an order is rejected, NPC and Idenix will cooperate in good faith to resolve any
supply issues raised by such order.

          3.3. Delivery.

          (a) NPC shall supply the Packaged Product in response to each order
placed in accordance with the terms of this Packaging Agreement by Idenix,
provided, that such order will be deemed to have been fully satisfied if the
quantity of the Packaged Product supplied is not more than [**] percent ([**]%)
and not less than [**] percent ([**]%) of the quantity of Packaged Product
ordered. NPC shall deliver orders on the requested delivery date. In the event
delivery of any ordered shipment is delayed by more than [**] days, Idenix will,
in addition to other remedies, be entitled to revise its forecasts and
reschedule orders under Section 3.1 and Section 3.2 to address such delay in a
reasonable manner without penalty to Idenix. If NPC anticipates a problem
supplying the required quantities, NPC and Idenix shall in good faith discuss
and determine the best way to handle the situation.

          (b) All Packaged Product delivered under this Packaging Agreement will
be delivered [**] the Packaging site to such location designated by Idenix in
the

                                        6

<PAGE>

applicable purchase order. Idenix will pay all freight, insurance charges,
taxes, duties, inspection fees and other charges applicable to the supply and
transport of Packaged Product supplied to Idenix. The Parties agree that Idenix
retains title and, except as otherwise provided herein, retains throughout the
Packaging process the risk of loss of, and damage to, Bulk Product. In the event
loss of, or damage to, the Packaged Product after delivery to the carrier,
Idenix will be responsible to file claims with the carrier. NPC will cooperate
with Idenix in the filing and prosecution of such claims.

          3.4. Acceptance and Rejection.

          (a) Acceptance. Idenix shall notify NPC in writing within timelines
specified in the Quality Agreement of any apparent non-conformity of the
Packaged Product to the applicable Specifications (a "Rejection") and Idenix
shall return to NPC, at Idenix's expense, samples of the rejected Packaged
Product with a reasonably detailed statement of the claimed defect. If Idenix
fails to so notify NPC, Idenix will be deemed to have accepted such Packaged
Product; provided that if the non-conformity results from a defect that is not
typically observed by routine inspection, Idenix will have the right to reject
such Packaged Product if it notifies NPC of such Rejection within the timelines
specified in the Quality Agreement.

          (b) Disputes regarding Rejection. Upon receipt of a Rejection, NPC
shall have twenty (20) Business Days to advise Idenix by notice in writing if it
disagrees with such Rejection (a "Rejection Disagreement"). If the Parties fail
to agree within ten (10) Business Days after Idenix' receipt of a Rejection
Disagreement, the Parties shall mutually select an independent laboratory to
evaluate the samples returned by Idenix. Such evaluation shall be binding on the
Parties. If such evaluation certifies that any of such samples do not conform to
the applicable Specifications, NPC shall pay the costs and expenses of such
evaluation, all costs and expenses incurred by Idenix in returning the samples
of the rejected Packaged Product and all costs incurred in replacing the
non-conforming Packaged Product. If such evaluation certifies that all such
samples conform to the applicable Specifications, Idenix shall pay the costs and
expenses of such evaluation and shall pay NPC the Fee for the rejected Packaged
Product.

          (c) Consequences of accepted or non-disputed Rejection. Idenix will
not be required to pay NPC for any Packaged Product that does not conform to the
applicable Specifications. NPC shall, at its expense, replace any non-conforming
Packaged Product that does not conform to the applicable Specifications [**].

          3.5. Secondary Supplier. Idenix and NPC shall work together to
identify and appoint a Secondary Supplier.

                                        7

<PAGE>

                                   ARTICLE IV
                         REPRESENTATIONS AND WARRANTIES

          4.1. Representations and Warranties of NPC.

          NPC hereby represents and warrants to Idenix that

          (a) Product. The Packaging of all Bulk Product delivered pursuant to
the terms hereof by NPC to Idenix or its designee during the Term shall at
delivery be in compliance with the Specifications and the requirements pursuant
to the Quality Agreement.

          (b) Authorization. This Packaging Agreement has been duly executed and
delivered by NPC. This Packaging Agreement, assuming it constitutes a valid and
legally binding obligation of Idenix, constitutes a valid and binding obligation
of NPC, enforceable against NPC in accordance with its terms, except as
enforceability may be limited by applicable bankruptcy, fraudulent transfer,
insolvency, moratorium or other similar laws relating to or affecting creditors'
rights generally or by equitable principles, including those limiting the
availability of specific performance, injunctive relief and other equitable
remedies and those providing for equitable defenses. The execution, delivery and
performance of this Packaging Agreement has been duly authorized by all
necessary corporate action on the part of NPC and its respective officers and
directors.

          (c) Absence of Conflicts. The execution, delivery and performance of
this Packaging Agreement by NPC, the consummation by NPC of the transactions
contemplated hereby and the compliance by NPC with the provisions hereof do not
conflict with or constitute a default under any agreement, instrument or
understanding, oral or written to which it is a party or by which it may be
bound, does not conflict with any provision of any of its organizational
documents and does not conflict with or violate any applicable Law.

          (d) Organization and Standing. NPC is a corporation, duly organized,
validly existing and in good standing under the Laws of the State of Delaware.

          (e) Power and Authority. NPC has corporate power and authority to
execute, deliver and perform this Packaging Agreement and to consummate the
transactions contemplated hereby.

          (f) Facility Warranty. NPC hereby represents and warrants to Idenix
that any of its facilities at which the Bulk Product is Packaged has and shall
retain all necessary approvals of the FDA to Package the Bulk Product at such
facility. NPC further represents and warrants that, to the best of its
knowledge, it is not currently subject to any regulatory enforcement activity
which, if determined adversely to NPC, would prohibit or restrict NPC's
performance of its obligations arising pursuant to this Packaging Agreement.

                                        8

<PAGE>

          (g) Personnel Warranty. NPC represents that no person employed by NPC
in connection with this Packaging Agreement has been debarred under Subsection
(a) or (b) of Section 306 of the Federal Food, Drug and Cosmetic Act (21 USC
335a) and that no person who has been debarred under Subsection (a) or (b) of
Section 306 of said Act will be employed by NPC in connection with this
Packaging Agreement.

          4.2. Representations and Warranties of Idenix. Idenix hereby
represents and warrants to NPC:

          (a) Authorization. This Packaging Agreement has been duly executed and
delivered by Idenix. This Packaging Agreement, assuming it constitutes a valid
and legally binding obligation of NPC, constitutes a valid and legally binding
obligation of Idenix, enforceable against it in accordance with its terms except
as enforceability may be limited by applicable bankruptcy, fraudulent transfer,
insolvency, moratorium or other similar Laws relating to or affecting creditors'
rights generally or by equitable principles, including those limiting the
availability of specific performance, injunctive relief and other equitable
remedies and those providing for equitable defenses. The execution, delivery and
performance of this Packaging Agreement has been duly authorized by all
necessary corporate action on the part of Idenix and its respective officers and
directors.

          (b) Absence of Conflicts. The execution, delivery and performance of
this Packaging Agreement by Idenix, the consummation by Idenix of the
transactions contemplated hereby and the compliance by Idenix with the
provisions hereof do not conflict with or constitute a default under any
agreement, instrument or understanding, oral or written to which it is a party
or by which it may be bound, does not conflict with any provision of any
organizational documents of Idenix and does not conflict with or violate any
applicable Law.

          (c) Organization and Standing. Idenix is a corporation, duly
organized, validly existing and in good standing under the Laws of the State of
Delaware.

          (d) Power and Authority. Idenix has full corporate power and authority
to execute, deliver and perform this Packaging Agreement and to consummate the
transactions contemplated hereby.

          4.3. Disclaimer. EXCEPT AS EXPRESSLY STATED IN THIS PACKAGING
AGREEMENT, NEITHER PARTY MAKES ANY REPRESENTATION OR EXTENDS ANY WARRANTY OF ANY
KIND, EITHER EXPRESS OR IMPLIED, TO THE OTHER PARTY, INCLUDING ANY WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

                                    ARTICLE V
                                QUALITY ASSURANCE

                                        9

<PAGE>

          5.1. Quality Agreement. The provisions of the quality agreement (the
"Quality Agreement"), attached hereto as Exhibit 2, are incorporated herein by
reference.

                                   ARTICLE VI
                               PRICE AND PAYMENTS

          6.1. Fee. The fee payable by Idenix to NPC for Packaging the Bulk
Product and conducting its other activities in accordance with this Packaging
Agreement shall be equivalent to the total of (i) Fully Allocated Manufacturing
Costs, and (ii) and a mark-up of [**] percent ([**]%) of the Fully Allocated
Manufacturing Costs (collectively, the "Fee"). Such Fee shall be exclusive of
any applicable sales or other tax.

          6.2. Invoices. Upon dispatch of each shipment of Packaged Product to
Idenix, NPC will send an invoice to Idenix for the Fee related to such shipment.
Such invoice will be sent to an address specified in writing by Idenix to NPC.
Idenix will pay each such invoice within thirty (30) days of the delivery of
such shipment by check or electronic funds transmission in U.S. Dollars as
specified in any such invoice, without any offset or deduction of any nature
whatsoever. All payments will be made to such account as NPC will have specified
in writing to Idenix with written confirmation of payment sent by facsimile to
such address as NPC will have specified in writing to Idenix.

          6.3. Interest. If Idenix fails to pay any invoiced amount when due, a
service charge will be imposed by NPC equal to the lesser of [**] percent
([**]%) of the unpaid amount per month or the highest rate permitted by
applicable Law, compounded monthly, calculated on the number of days for which
such amountpayments remains unpaid.

          6.4. Separate Sale. Each delivery of Packaged Product to Idenix will
constitute a separate shipment, obligating Idenix to pay therefor, whether said
shipment is in whole or only partial fulfillment of any order or confirmation
issued in connection therewith.

          6.5 Audit. NPC shall keep, and shall cause its Affiliates to keep,
complete and accurate records of the data, including expense data, relating to
the reports and payments required under this Packaging Agreement. Idenix will
annually have the right, at its own expense, to have an independent, certified
public accountant, selected by Idenix and reasonably acceptable to NPC, review
any such records pertaining to the Fee in the location(s) where such records are
maintained by NPC or its Affiliates, upon reasonable advance written notice and
during regular business hours and under obligations of confidentiality
reasonably acceptable to NPC, for the sole purpose of verifying the basis and
accuracy of invoices made pursuant to this Article VI in the calendar year
preceding such audit request. If the review of such records reveals that NPC
failed to accurately report information pursuant to this Article VI, then NPC
shall

                                       10

<PAGE>

promptly reimburse to Idenix any overpayments by Idenix, together with interest
calculated in the manner provided for in Section 6.3.

                                   ARTICLE VII
                                    INSURANCE

          7.1. Insurance. At all times from the Effective Date through that date
which is three years after the expiration date for each Packaged Product
supplied to Idenix hereunder, Idenix and NPC will each maintain product
liability insurance in an amount of not less than $1,000,000 per occurrence,
$5,000,000 annual aggregate. The insurance obligations hereunder may be met,
partly or entirely, by a program of self-insurance.

                                  ARTICLE VIII
                              TERM AND TERMINATION

          8.1. Term. This Packaging Agreement will commence on the Effective
Date and remain in force and effect until terminated by either Party in
accordance with this Article VIII (the "Term").

          8.2. Termination. Either Party will have the right to terminate this
Packaging Agreement with or without cause effective anytime after the third
anniversary of the Effective Date with twelve (12) month prior written notice.

          8.3. Termination For Material Breach. Upon any material breach of this
Packaging Agreement by either Party (the "Breaching Party"), the other Party
(the "Non-Breaching Party") may, by providing thirty (30) days' written notice
to the Breaching Party, terminate this Packaging Agreement. The termination
shall become effective at the end of the notice period unless the Breaching
Party cures such breach during such notice period. Notwithstanding the
foregoing, if such breach, by its nature, is incurable, the Non-Breaching Party
may terminate this Packaging Agreement immediately upon written notice to the
Breaching Party.

          8.4. Insolvency. This Agreement may be terminated upon thirty (30)
days' prior written notice by either Party at any time during this Packaging
Agreement if the other Party files in any court pursuant to any statute of any
government in any country a petition in bankruptcy or insolvency or for
reorganization or for an arrangement or for the appointment of a receiver or
trustee of the Party or of its assets; or if any Person proposes a written
agreement of composition for extension of such other Party's debts; or if the
other Party shall be served with an involuntary petition against it, filed in
any insolvency proceeding, and such petition shall not be dismissed within sixty
(60) days after filing thereof; or if the other Party shall be a party to any
dissolution or liquidation; or if the other Party shall make a general
assignment for the benefit of its creditors; or if the other Party is subject to
any final order regarding insolvency or bankruptcy which can

                                       11

<PAGE>

be expected to have a material adverse effect on the Packaging and/or supply of
Packaged Product.

          8.5. Effect of Termination. If this Packaging Agreement is terminated
pursuant to Sections 8.2, 8.3 or 8.4:

          (a) all financial obligations under this Packaging Agreement existing
as of the effective date of such termination shall remain in effect until
fulfilled;

          (b) except as set forth in this Section 8.5, all of the Parties'
obligations under this Packaging Agreement shall terminate;

          (c) Idenix acknowledges and agrees that, if NPC terminates this
Packaging Agreement pursuant to Section 8.3 or 8.4, NPC will be entitled to
cancel any order accepted prior to the date notice of termination is given, and
will not be obligated to ship any Packaged Product ordered by Idenix pursuant to
such order except as such Packaged Product may be included in those shipped
pursuant to Section 8.5 (g) below.

          (d) If NPC terminates this Packaging Agreement pursuant to Section 8.3
or 8.4 and if Idenix will default in the payment of any indebtedness to NPC when
and as the same will become due and payable, and if such default will continue
for a period of ten (10) Business Days after written notice of such default will
have been given to Idenix, then all of the Fee payment obligations of Idenix to
NPC, whether then due or not, will become immediately due and payable.

          (e) The termination of this Packaging Agreement will not release
Idenix from the obligation to pay any sum that it may be owing to NPC (whether
then or thereafter due to NPC) or operate to discharge any liability that had
been incurred by either Party prior to any such termination.

          (f) If NPC terminates this Packaging Agreement pursuant to Section 8.3
or 8.4, during the period between the giving of any notice of termination
pursuant to this Article VIII and the effective date of the termination as set
forth in such notice, all Packaged Product will be delivered to Idenix solely on
a C.O.D. basis.

          (g) Upon termination of this Packaging Agreement, NPC (i) will
transfer, or will cause to be transferred, all remaining Packaged Product and
work in process relating to the Packaging of the Bulk Product and Packaging
Materials acquired in reasonable quantities during the Term to fulfill NPC's
obligations hereunder but only to fulfill NPC's obligations hereunder, by
delivery to Idenix of all Packaged Product at the price determined in accordance
with Article VI, and (ii) will return to Idenix all consigned Bulk Product on
hand at NPC.

          (h) It is understood and agreed that Idenix will be responsible for
all Packaging of the Bulk Product after termination of this Packaging Agreement.

                                       12
<PAGE>

          (i) Termination of this Packaging Agreement will not relieve the
Parties hereto of any obligation accruing prior to such termination. The rights
and obligations of the parties hereto under Section 6.5, Articles IV, VII, VIII,
IX, X, XI and XII, and, with respect to any Packaged Product supplied prior to
the termination of this Packaging Agreement or pursuant to Section 8.5(g) of
this Packaging Agreement, Sections 3.4, 4.1(a) and 7.1 of this Packaging
Agreement will survive the termination of this Packaging Agreement.

                                   ARTICLE IX
                                  FORCE MAJEURE

          9.1. Force Majeure. Except as otherwise expressly set forth in this
Packaging Agreement, neither Party will be deemed to have defaulted under or
breached this Packaging Agreement for failure or delay in fulfilling or
performing any term or provision of this Packaging Agreement (other than the
payment of money) when such failure or delay will be caused (directly or
indirectly) by: any act of God, accident, explosion, fire, storm, sabotage,
earthquake, flood, drought, peril of the sea, riot, embargo, war, any Law of
general application, seizure, requisition or allocation, any failure or delay of
transportation, shortage of or inability to obtain supplies, equipment, fuel or
labor, labor strike by common carriers or by the delayed Party's employees or
agents, or any other circumstance or event beyond the reasonable control of the
Party relying upon such circumstances or event to excuse such Party's delay or
failure to perform hereunder. Such Party shall be so excused only during the
period of such circumstance or event and such Party shall use Commercially
Reasonable Efforts to remedy such situation and commence compliance with this
Packaging Agreement as soon as possible notwithstanding such circumstance or
event.

                                   ARTICLE X
                                 CONFIDENTIALITY

          10.1. Confidential Information; Exceptions. Except to the extent
expressly authorized by this Packaging Agreement or otherwise agreed in writing,
the Parties agree that the receiving Party shall keep confidential (except to
the extent reasonably necessary for regulatory approval of the Packaged Products
or for the filing, prosecution and maintenance of patent rights), and shall not
publish or otherwise disclose or use for any purpose other than as provided for
in this Packaging Agreement without the prior written consent of the disclosing
Party, any information or materials, including, without limitation, proprietary
information and materials (whether or not patentable) regarding the other
Party's technology, products, business information or objectives, that is
designated as confidential by the disclosing Party or is treated as confidential
by the disclosing Party in the regular course of business such whether furnished
to the receiving Party, directly or indirectly, by the other Party or learned by
the receiving Party from or through its exercise of its rights pursuant to this
Packaging Agreement (collectively,

                                       13

<PAGE>

"Confidential Information"), except to the extent that the Confidential
Information (as determined by competent evidence):

          (a) was already known to, or used by, the receiving Party at the time
of disclosure by the disclosing Party;

          (b) either before or after the date of the disclosure to the receiving
Party, becomes published or generally known to the public (including information
known to the public through the sale of products in the ordinary course of
business), without the receiving Party or its Affiliates, consultants or
advisors violating this Article X;

          (c) either before or after the date of the disclosure to the receiving
Party, is lawfully disclosed to the receiving Party by sources other than the
disclosing Party rightfully in possession of the Confidential Information;

          (d) is independently developed by or for the receiving Party without
reference to or reliance upon the Confidential Information.

          Notwithstanding anything set forth herein to the contrary, this
Article X shall not prohibit the receiving Party from disclosing Confidential
Information of the disclosing Party that is required to be disclosed by the
receiving Party to comply with applicable Laws, to defend or prosecute
litigation or to comply with governmental orders or regulations; provided that,
to the extent practicable, the receiving Party provides prior written notice of
such disclosure to the disclosing Party and assists the disclosing Party in its
reasonable and lawful efforts to avoid and/or minimize the degree of such
disclosure.

          10.2. Employee and Advisor Obligations. Each Party agrees that it
shall provide Confidential Information received from the other Party only to its
employees, consultants and advisors, and to the employees, consultants and
advisors of such Party's Affiliates, who have a need to know and have an
obligation to treat such information and materials as confidential under terms
no less restrictive than those set forth herein.

          10.3. Term. All obligations of confidentiality imposed under this
Article X shall expire five (5) years following the later of termination of this
Packaging Agreement and expiration or termination of the last to expire or
terminate other agreement between the Parties, and/or Novartis Pharma AG and
Idenix, with respect to the Packaged Product.

          10.4. Publicity. Neither Party shall issue any press release or public
announcement relating to any Bulk Product or Packaged Products in the Territory
or this Packaging Agreement without the prior written approval of the other
Party or, with respect to NPC, an Affiliate of NPC, which approval shall not be
unreasonably withheld, except that a Party may issue such a press release or
public announcement if required by Law, including without limitation by the
rules or regulations of the United States Securities and Exchange Commission or
similar regulatory agency in a country other than

                                       14

<PAGE>

the United States or of any stock exchange or Nasdaq; provided that the other
Party has received prior notice of such intended press release or public
announcement if practicable under the circumstances and the Party subject to the
requirement includes in such press release or public announcement only such
information relating to the Bulk Product or Packaged Product or this Packaging
Agreement as is required by such Law. The rights of approval and notice granted
to a Party in accordance with the preceding sentence shall only apply for the
first time that specific information is to be disclosed, and shall not apply to
the subsequent disclosure of substantially similar information that has
previously been disclosed.

                                   ARTICLE XI
                                 INDEMNIFICATION

          11.1. By NPC. NPC will indemnify, defend and hold harmless Idenix and
its Affiliates and their respective officers, directors, employees, agents, at
NPC's cost and expense, from and against any and all Losses arising out of (a)
any breach by NPC of any of its representations and warranties, covenants or
obligations contained in this Packaging Agreement or (b) the negligence or
willful misconduct of NPC or its Affiliates, or any of their respective
directors, officers, employees and agents, in the performance of obligations or
exercise of rights under this Packaging Agreement (except to the extent caused
by a breach by Idenix of its representations, warranties or obligations pursuant
to this Packaging Agreement).

          11.2. By Idenix. Idenix will indemnify, defend and hold harmless NPC
and its Affiliates and their respective officers, directors, employees, agents,
at Idenix' cost and expense, from and against any and all Losses arising out of
(i) a breach by Idenix of any of its representations and warranties, covenants
or obligations contained in this Packaging Agreement, or (ii) the negligence or
willful misconduct of Idenix or its Affiliates, or any of their respective
directors, officers, employees and agents, in the performance of obligations or
exercise of rights under this Packaging Agreement.

          11.3. Procedures. If any claim, demand, action or proceeding is made
or commenced by any Third Party (a "Third-Party Claim") against any person that
is entitled to be indemnified with respect thereto under this Article XI (an
"Indemnified Party"), the Indemnified Party shall give the Party obligated to
provide the indemnity (the "Indemnifying Party") prompt written notice thereof
or, if earlier, upon the assertion of any such claim by a Third Party); provided
that the failure to give such written notice shall not affect the
indemnification obligation of the Indemnifying Party under this Packaging
Agreement except and only to the extent such Indemnifying Party is actually
prejudiced as a result of such failure to give notice. Within thirty (30) days
after delivery of such notification, the Indemnifying Party may, upon written
notice thereof to the Indemnified Party, assume control of the defense of such
action, suit, proceeding or claim with counsel reasonably satisfactory to the
Indemnified Party. If the Indemnifying Party does not assume control of such
defense, the Indemnified Party shall control such

                                       15

<PAGE>

defense. The Party not controlling such defense shall have the right to
participate in the defense of the Third-Party Claim at its own expense through
counsel of its choice; provided that if the Indemnifying Party assumes control
of such defense and the Indemnified Party reasonably concludes, based on advice
from counsel, that the Indemnifying Party and the Indemnified Party have
conflicting interests with respect to such action, suit, proceeding or claim,
the Indemnifying Party shall be responsible for the reasonable fees and expenses
of counsel to the Indemnified Party solely in connection therewith; provided
further, however, that in no event shall the Indemnifying Party be responsible
for the fees and expenses of more than one counsel in any one jurisdiction for
all Indemnified Parties. The Party controlling such defense shall keep the other
Party advised of the status of such action, suit, proceeding or claim and the
defense thereof and shall consider recommendations made by the other Party with
respect thereto. The Indemnified Party shall not agree to any settlement of such
action, suit, proceeding or claim without the prior written consent of the
Indemnifying Party, which shall not be unreasonably withheld. The Indemnifying
Party shall not consent to any settlement of such action, suit, proceeding or
claim or consent to any judgment in respect thereof that would imposes any
liability or obligation on the Indemnified Party or which does not completely
and unconditionally release the Indemnified Party from all liability in respect
of the Third-Party Claim without the prior written consent of the Indemnified
Party.

                                   ARTICLE XII
                                  MISCELLANEOUS

          12.1. LIMITATION ON LIABILITY. NEITHER NPC's OR IDENIX' WILL BE LIABLE
TO THE OTHER FOR PUNITIVE, EXEMPLARY, SPECIAL, MULTIPLE, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, WARRANTY, NEGLIGENCE, TORT, STRICT
LIABILITY OR OTHERWISE, ARISING OUT OF OR RELATING TO THIS PACKAGING AGREEMENT
OR THE EXERCISE OF ITS RIGHTS HEREUNDER, OR FOR LOST PROFITS ARISING FROM OR
RELATING TO ANY BREACH OF THIS AGREEMENT, REGARDLESS OF ANY NOTICE OF SUCH
DAMAGES, EXCEPT WHERE SUCH DAMAGES OR LOST PROFITS ARE REQUIRED TO BE PAID TO A
THIRD PARTY BY AN INDEMNIFYING PARTY UNDER ARTICLE XI; PROVIDED, HOWEVER, THIS
EXCLUSION IS NOT INTENDED TO, NOR WILL, EXCLUDE ACTUAL OR COMPENSATORY DAMAGES
OF THE AFFECTED PARTY.

          12.2. Assignment. Neither Idenix nor NPC may assign this Packaging
Agreement in whole or in part without the consent of the other Party; provided
that (a) either Party may assign this Packaging Agreement to an Affiliate on the
condition that the assigning Party shall remain primarily liable hereunder for
the prompt and punctual payment and performance of all obligations of the
assignee, and (b) this Packaging Agreement may be assigned by a Party to a Third
Party in connection with a sale or transfer of all or substantially all of such
Party's business to which this Packaging

                                       16

<PAGE>

Agreement relates. This Packaging Agreement shall be binding upon, and shall
inure to the benefit of, all permitted successors and assigns.

          12.3. Subcontracting. NPC shall have the right to subcontract any of
its obligations hereunder to a Third Party only with the prior written consent
of Idenix, such consent not to be unreasonably withheld, delayed or conditioned,
provided, however, that NPC may subcontract any of its obligations hereunder
other than the obligation to Package without Idenix' consent. In either case,
NPC shall procure that the terms of the subcontract are not inconsistent with
the terms of this Packaging Agreement. Furthermore, NPC shall procure that the
confidentiality provisions of the subcontract are no less onerous than the
confidentiality provisions set forth herein. NPC shall remain liable under this
Packaging Agreement until such obligations are satisfied.

          12.4. Severability. If any provision of this Packaging Agreement is
held to be illegal, invalid or unenforceable by any Law or public policy, the
remaining provisions of this Packaging Agreement will nevertheless remain in
full force and effect and will not be affected by the illegal, invalid or
unenforceable provision or by its severance herefrom so long as the economic or
legal substance of the transactions contemplated hereby is not affected in any
manner materially adverse to any Party. Upon such determination that any term or
other provision is invalid, illegal or unenforceable, the Parties will negotiate
in good faith to modify this Packaging Agreement so as to effect the original
intent of the Parties as closely as possible in an acceptable manner in order
that the transactions contemplated hereby are consummated as originally
contemplated to the greatest extent possible.

          12.5. Notices. All notices or other communications which are required
or permitted hereunder will be in writing and delivered personally, sent by
telecopier (and promptly confirmed by personal delivery, registered or certified
mail or overnight courier), sent by nationally-recognized overnight courier or
sent by registered or certified mail, postage prepaid, addressed as follows:

          If to NPC, to:

          Novartis Pharmaceuticals Corporation
          59 Route 10
          East Hanover, NJ 07936
          Attn: James A. Edwards
                Vice President - U.S. Supply Chain Management
          Telephone: (862) 778-5599
          Facsimile: (973) 781-5324

                                       17

<PAGE>

          with a copy (which will not constitute notice) to:

          Novartis Pharmaceuticals Corporation
          59 Route 10
          East Hanover, NJ 07936
          Attn: General Counsel
          Telephone: (862) 778-5230
          Facsimile: (973) 781-5260

          If to Idenix, to:

          Idenix Pharmaceuticals, Inc.
          60 Hampshire Street
          Cambridge, MA 02139
          Attn: VP, Manufacturing
          Telephone: 617-995-9800
          Facsimile: 617-995-9801

          with a copy to:

          Idenix Pharmaceuticals, Inc.
          60 Hampshire Street
          Cambridge, MA 02139
          Attn: General Counsel
          Telephone: 617-995-9800
          Facsimile: 617-995-9801

or to such other address as the Party to whom notice is to be given may have
furnished to the other Party in writing in accordance herewith. Notice shall be
deemed to have been delivered upon personal delivery or (a) four (4) days after
deposit in the mail or the business day next following deposit with a reputable
overnight courier and (b) in the case of notices provided by telecopy (which
notice shall be followed immediately by an additional notice pursuant to clause
(a) above if the notice is of a default hereunder), upon completion of
transmissions to the addressee's telecopier.

          12.6. Applicable Law. This Packaging Agreement will be governed by and
construed in accordance with the Laws of the State of New York, without giving
effect to principles of conflict of Laws thereof.

          12.7. Entire Agreement. This Packaging Agreement and the attached
Schedules and Exhibits, which are incorporated herein, constitute the entire
agreement between the Parties with respect to the subject matter hereof and all
prior agreements with respect hereto are superseded. No amendment or
modifications hereof will be

                                       18

<PAGE>

binding upon the Parties unless set forth in a writing specified to be an
explicit amendment to this Packaging Agreement duly executed by authorized
representatives of each of the Parties hereto. The Parties recognize that,
during the Term, a purchase order, acknowledgement form or similar routine
document (collectively "Forms") may be used to implement or administer
provisions of this Packaging Agreement. Therefore, the Parties agree that the
terms of this Packaging Agreement will prevail in the event of any conflict
between this Packaging Agreement and the printed provision of such Forms, or
typed provisions of Forms that add to, vary, modify or are at conflict with the
provisions of this Packaging Agreement.

          12.8. Headings. The headings used in this Packaging Agreement are
intended for convenience only and will not be considered part of the written
understanding among the Parties and will not affect the construction of this
Packaging Agreement.

          12.9. Independent Contractors. It is expressly agreed that NPC, on the
one hand, and Idenix, on the other hand, will be independent contractors and
that neither the relationship among the Parties nor this Packaging Agreement
will be construed as creating a partnership, joint venture or agency. Neither
NPC, on the one hand, nor Idenix, on the other hand, will have the authority to
make any statements, representations or commitments of any kind, or to take any
action or to incur any liability or obligation which will be binding on the
other, without the prior written consent of the other Party to do so. All
persons employed by a Party will be employees of such Party and not of the other
Party and all costs and obligations incurred by reason of any such employment
will be for the account and expense of such Party. Neither Party shall have any
responsibility for the hiring, firing or compensation of the other Party's
employees or for any such employee's employee benefits.

          12.10. Waiver. The waiver by either Party of any right hereunder or
the failure to perform or of a breach by the other Party will not be deemed a
waiver of any other right hereunder or of any other breach or failure by said
other Party whether of a similar nature or otherwise.

          12.11. Counterparts. This Packaging Agreement may be executed in two
or more counterparts, each of which will be deemed an original, but all of which
together will constitute one and the same instrument even if both Parties have
not executed the same counterpart. Signatures provided by facsimile transmission
shall be deemed to be original signatures.

          12.12. Dispute Resolution. The Parties shall negotiate in good faith
and use reasonable efforts to settle any dispute arising from or related to this
Packaging Agreement or the breach thereof. If the Parties do not fully settle,
and a Party wishes to pursue the matter, each such dispute shall be resolved as
follows:

                                       19

<PAGE>

          (a) Executive Officers. The Executive Officers shall meet to attempt
to resolve such dispute.

          (b) Arbitration.

          (i) If the Executive Officers do not resolve such dispute within ten
     (10) Business Days after either Party requests such a meeting, either Party
     may make a written demand for formal dispute resolution and such dispute
     shall be settled by arbitration administered by the American Arbitration
     Association ("AAA") under its Commercial Arbitration Rules, in each case,
     not inconsistent with the terms of this Packaging Agreement, and judgment
     on the award rendered by the arbitrators may be entered in any court having
     jurisdiction thereof.

          (ii) The arbitration shall be conducted in English in New York, New
     York, if initiated by Idenix, or Boston, Massachusetts, if initiated by
     NPC, by a panel of three (3) persons experienced in the pharmaceutical
     business: within thirty (30) days after initiation of arbitration, each
     Party shall select one (1) person to act as arbitrators and the two (2)
     Party-selected arbitrators shall select a third arbitrator within five (5)
     days of their appointment. If the arbitrators selected by the Parties are
     unable or fail to agree upon the third arbitrator, the third arbitrator
     shall be appointed by the AAA as soon as practicable.

          (iii) Within ten (10) days after the designation of the arbitrators
     pursuant to Section 12.13(b)(ii) (the "Proposed Resolution Deadline"), each
     Party shall submit to the arbitrators and to the other Party a statement of
     all disputed issues and a proposed ruling on the merits of each such issue
     together with a brief or other written memorandum supporting the merits of
     its resolution.

          (iv) The arbitrators and the Parties shall then meet within five (5)
     days after the Proposed Resolution Deadline, at which time each Party shall
     have one hour to argue in support of its proposed resolution. The Parties
     shall not call any witnesses in support of their arguments. The Parties
     shall have the right to be represented by counsel.

          (v) The arbitrators shall use their best efforts to rule on the
     dispute within two (2) Business Days thereafter. The arbitrators shall
     resolve the dispute by a vote of the majority of the arbitrators selecting
     one of the two (2) proposed resolutions in its entirety, without
     substitution, deletion, addition or amendment. Such selected resolution
     shall be binding and conclusive upon the Parties. All rulings of the
     arbitrators shall be in writing and shall be delivered to the Parties. The
     arbitrators shall have no authority to award punitive or any other type of
     damages not measured by a Party's compensatory damages and demanded in its
     proposed resolution.

                                       20

<PAGE>

          (vi) Either Party may apply to the arbitrators for interim injunctive
     relief until the arbitration award is rendered or the dispute is otherwise
     resolved. Either Party also may, without waiving any remedy under this
     Packaging Agreement, seek from any court having jurisdiction any injunctive
     or provisional relief necessary to protect the rights or property of that
     Party pending the arbitration award.

          (vii) The Party whose proposed resolution was not selected by the
     majority vote of the arbitrators shall pay the full costs of the
     arbitration and the reasonable costs and expenses of the prevailing Party,
     including, without limitation, reasonable attorneys' fees and travel and
     lodging costs.

          (viii) Except to the extent necessary to confirm an award or as may be
     required by law, neither a Party nor an arbitrator may disclose the
     existence, content, or results of an arbitration without the prior written
     consent of both Parties.

          (ix) In no event shall an arbitration be initiated after the date when
     commencement of a legal or equitable proceeding based on the dispute,
     controversy or claim would be barred by the applicable New York statute of
     limitations.

                  [Remainder Of Page Intentionally Left Blank]

                                       21

<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Packaging
Agreement to be signed by their respective representatives thereunto duly
authorized, all as of the date first written above.

                                        NOVARTIS PHARMACEUTICALS CORPORATION

                                        By:    /s/ James Edwards
                                            ------------------------------------
                                        Name:  James Edwards
                                              ----------------------------------
                                        Title: V.P. Supply Chain Management
                                               ---------------------------------

                                        IDENIX PHARMACEUTICALS, INC.

                                        By: /s/ Jean-Pierre Sommadossi
                                            ------------------------------------
                                            Jean-Pierre Sommadossi
                                            Chairman and Chief Executive Officer

           [Signature Page to Packaging Agreement Dated June 22, 2006]

                                       22

<PAGE>

                                    EXHIBIT 1
                                   BATCH SIZE

<TABLE>
<CAPTION>
Product                      Batch Size
-------                      ----------
<S>                          <C>
Telbivudine 600mg 30 count   [**] bottles
</TABLE>

                                       23

<PAGE>

                                    EXHIBIT 2
                                QUALITY AGREEMENT

                                       24
<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

                                     Between

                   IDENIX PHARMACEUTICALS, INC., CAMBRIDGE USA
                  as contract giver, subsequently named IDENIX

                                       and

           NOVARTIS PHARMACEUTICALS CORPORATION, EAST HANOVER, NJ, USA
                as contract acceptor, subsequently named NOVARTIS

                                  First edition

                                                                             1/1

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                          <C>
   TABLE OF ENCLOSURES....................................................     3

   PREAMBLE...............................................................     4

1  SCOPE of the Agreement.................................................     4

2  Documents..............................................................     4
   2.1 Directives.........................................................     4
   2.2 Packaging Instructions, Specifications.............................     4
   2.3 Computer System Validation and Electronic Records..................     4

3  Change Management and Approval.........................................     4
   3.1 Approval of Changes to this Agreement..............................     5
   3.2 Approval of Changes................................................     5

4  Information Flow.......................................................     5
   4.1 Inspections........................................................     5
   4.2 Complaints.........................................................     6
   4.3 Recalls............................................................     6
   4.4 Product Quality Review.............................................     6
   4.5 Handling of Deviations.............................................     6

5  Instrument Qualification and Validation................................     6

6  Transport and Incoming product inspection..............................     6

7  Testing and Release of Packaging Components............................     7

8  PACKAGING of PRODUCTS..................................................     7
   8.1 Packaging Instructions.............................................     7
   8.2 Packaging Records..................................................     7
   8.3 Review of Batch Documentation......................................     7
   8.4 Storage and Packaging for Dispatch.................................     7
   8.5 Transport..........................................................     7
   8.6 Defective Products.................................................     8
   8.7 Release of Products to the Market..................................     8
   8.8 Stability Testing..................................................     8

9  Retention of Samples and Documentation.................................     8
</TABLE>

                                    4-AUG-06

                                                                             2/2

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

<TABLE>
<S>                                                                          <C>
10 Waste Material.........................................................     8

11 Term and expiration of the QA agreement................................     9

12 DEFINITIONS............................................................     9

13 List of Enclosures.....................................................     9

14 Signature:.............................................................    10
</TABLE>

TABLE OF ENCLOSURES

<TABLE>
<S>                                                                          <C>
ENCLOSURE A: List of QA/QC Liaisons.......................................    11
ENCLOSURE B: Table of Responsibilities....................................    12
ENCLOSURE C: List of Products.............................................    14
ENCLOSURE D: Directives, Manufacturing and Testing Documents..............    15
</TABLE>

                                                                             3/3
<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

PREAMBLE

IDENIX and NOVARTIS have entered into that certain Packaging Agreement dated ___
(the "Packaging Agreement"). Under the Packaging Agreement, NOVARTIS will
provide Packaging for IDENIX at its packaging facilities in Suffern (USA) and
other related services for IDENIX.

IDENIX and NOVARTIS are to define their roles and responsibilities according to
the intentions of the EU/PIC GMP Guidelines. In addition to the requirements
below NOVARTIS will assure that the US Code of Federal Regulations and the
corresponding national guidelines prevailing at the time of the manufacture are
followed.

1    SCOPE OF THE AGREEMENT

This agreement defines contacts for all technical and quality matters (see
Enclosure A: List of QA/QC Liaisons), assigns the roles and responsibilities of
both parties (see Enclosure B: Table of Responsibilities). This agreement
establishes the reliance of IDENIX on the decisions made by NOVARTIS for the
Packaging (see Enclosure C: List of Products). It defines the packaging
instructions and applicable directives (see Enclosure D).

2    DOCUMENTS

2.1  DIRECTIVES

If not otherwise defined in this agreement the provisions of NOVARTIS' quality
management system and standard operating procedures shall be applied to
NOVARTIS' operations.

2.2  PACKAGING INSTRUCTIONS, SPECIFICATIONS

The packaging instructions are binding and have to be applied in detail. If
IDENIX'S specifications are incorporated into NOVARTIS' documentation, NOVARTIS
will assure that these conversions are accurate and updated as appropriate. In
addition, where possible, there should be a cross-reference in the master
document to the appropriate IDENIX specification(s).

2.3  COMPUTER SYSTEM VALIDATION AND ELECTRONIC RECORDS

NOVARTIS is responsible that computer systems used for the packaging operations
are validated. Approved validation protocols, reports, testing protocols & raw
data and system operation procedures shall be available for inspection by
IDENIX.

3    CHANGE MANAGEMENT AND APPROVAL

A change to be considered include changes to the agreement itself and changes
relevant to the registration of products, such as to the packaging location,
stability testing location, filed

                                                                             4/4

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

stability protocols and packaging materials used. Furthermore, changes that
could interfere with the quality of the products, such as to the testing
procedures, instructions and specifications.

3.1  APPROVAL OF CHANGES TO THIS AGREEMENT

Amendments and addenda to this agreement and its enclosures may be made only by
mutual agreement between the parties, and must be in writing.

3.2  APPROVAL OF CHANGES

IDENIX or NOVARTIS shall prepare a change request in writing. In this document,
the following items shall be defined at least:

-    a comparative description of the change (current versus intended status)

-    the rational for the change

-    a GMP assessment

-    a business (cost/benefit) evaluation

For each change, an approval from IDENIX is necessary before implementation.
Changes in specifications of material resulting from the update of compendia and
pharmacopoeia may be made by NOVARTIS without formal request and are notified to
IDENIX through the key-accounts (see Enclosure A) in a timely manner.

Registration relevant changes shall only be implemented after obtaining approval
from the national health authorities. NOVARTIS shall be informed by IDENIX well
in advance.

4    INFORMATION FLOW

4.1  INSPECTIONS

NOVARTIS agrees that its facilities, operations and quality systems are
inspected by IDENIX initially and at reasonable intervals (but no more than
[**]) thereafter in order to ensure coincidence with the registration of the
products and compliance with GMP guidelines and applicable IDENIX guidelines.
IDENIX may also conduct for cause audits regarding quality issues directly
related to the products. NOVARTIS will correct audit observations in a timely
manner where agreement is reached on such observations.

NOVARTIS shall allow foreign and local governmental authorities to inspect
facilities, operations and quality systems, as it is necessary to facilitate,
obtain or maintain the registration in the countries where IDENIX or its
affiliates, licensees or distributors, as the case may be, desire to sell the
products.

                                                                             5/5

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

NOVARTIS will immediately inform IDENIX about critical or major issues
encountered during authority inspections that might adversely affect the quality
of products manufactured for IDENIX and about the proposed corrective actions.

4.2  COMPLAINTS

IDENIX is responsible for handling complaints from the market and shall reply to
inquiries as promptly as possible. IDENIX shall provide the necessary
information within [**] business days to NOVARTIS and render assistance to
NOVARTIS as required. NOVARTIS shall without delay investigate technical
complaints and report results to IDENIX within [**] business days at the latest.
If the test period is unable to be met, NOVARTIS will notify IDENIX to arrange
an agreed upon timeframe.

4.3  RECALLS

In a potential recall situation both parties will consult each other and agree
on joint action. NOVARTIS shall co-operate in relation to the recall. IDENIX is
responsible for liaison with health authorities and conducts the recall
according to IDENIX' internal procedures.

4.4  PRODUCT QUALITY REVIEW

NOVARTIS will provide data for a Product Quality Review (PQR). IDENIX and
NOVARTIS will mutually agree on a format and reporting responsibility, template
and schedule of the PQR as laid down in Enclosure D.

4.5  HANDLING OF DEVIATIONS

Major deviations/failure investigations must be handled according to the
corresponding standard operation procedure and will be reported to and reviewed
by IDENIX. Minor deviations may be reported to IDENIX in the PQR.

5    INSTRUMENT QUALIFICATION AND VALIDATION

NOVARTIS agrees that packaging procedures must be validated and carried out
under GMP rules. Furthermore, the packaging instructions shall be followed using
calibrated and qualified equipment, computer systems and machines.

6    TRANSPORT AND INCOMING PRODUCT INSPECTION

IDENIX takes responsibility for transport from hand-over point of the bulk
product directly to NOVARTIS' packaging facilities using Novartis specified
broker and transporter. NOVARTIS will assure the inspection of the bulk material
(for transport damages, authentic seals etc.) and documentation (transport
documents, certificates etc.). Based on the results, NOVARTIS will

                                                                             6/6

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

release the material for further processing. NOVARTIS will inform IDENIX on any
deviation preventing packaging operations.

7    TESTING AND RELEASE OF PACKAGING COMPONENTS

Every batch of packaging materials used at NOVARTIS must be released for
production of the contractual products and be in compliance with the
specifications.

8    PACKAGING OF PRODUCTS

8.1  PACKAGING INSTRUCTIONS

NOVARTIS agrees that packaging of the products are carried out according to the
agreed packaging instructions.

8.2  PACKAGING RECORDS

NOVARTIS agrees that clear structured batch documentation for each packaging
operation is compiled and retained.

NOVARTIS assures that upon special requests from either Idenix or health
authorities the following documents will be provided as copies within two (2)
working days to IDENIX:

-    complete packaging record

-    certificate(s) of analysis of primary packaging materials and

-    test methods used.

8.3  REVIEW OF BATCH DOCUMENTATION

After review of the packaging documentation NOVARTIS is responsible that a
statement of compliance with GMP (CoC, confirmation statement) is provided to
IDENIX which is signed by a qualified person. A suitable format of this
statement or document will be mutually agreed.

8.4  STORAGE AND PACKAGING FOR DISPATCH

NOVARTIS is responsible that the requirements as referenced in Enclosure D
regarding the storage, labeling and packaging for dispatch of products are met.

8.5  TRANSPORT

Both parties agree that IDENIX is responsible for transport of the final
products (EXWORKS) and their distribution.

                                                                             7/7

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

8.6  DEFECTIVE PRODUCTS

IDENIX has the right to reject a batch, which does not meet the specifications
or is not packed according to the agreed procedures and GMP requirements. IDENIX
will inform NOVARTIS in writing of any defects not later than [**] business days
after receipt of the products. However, concealed defects, which are typically
not discovered by routine quality control measures, may be reported within [**]
business days after their discovery.

8.7  RELEASE OF PRODUCTS TO THE MARKET

The release of the products to the market is the responsibility of IDENIX. The
main responsibilities in this context are:

-    ensuring compliance with the marketing authorization,

-    certifying that the batch has been manufactured and tested in accordance
     with the relevant GMP guidelines, whereby IDENIX may fully or in part rely
     on the decisions made and information provided by NOVARTIS or NOVARTIS'
     associates,

-    deviations and changes have been authorized (internally and/or by
     regulatory authorities),

-    ensuring that the batch records and retained samples (of the finally packed
     product) are readily available in case of inquiries, investigations or
     recalls.

8.8  STABILITY TESTING

NOVARTIS is responsible for maintaining a follow-up stability program under ICH
conditions. IDENIX and NOVARTIS will mutually agree on a format, template and
schedule of the stability report and in accordance with the schedule to be
defined in Enclosure D. NOVARTIS may not make changes to filed stability
protocols or Test Methods without IDENIX approval (see also chapter 3). NOVARTIS
will investigate any stability failures and report results to IDENIX immediately
upon confirmation of the failing result.

9    RETENTION OF SAMPLES AND DOCUMENTATION

NOVARTIS ensures that samples and documentation related to the packaging are
retained as follows:

<TABLE>
<S>                            <C>
unprinted packaging material   [**] after initial release
Final packed product           [**]
</TABLE>

10   WASTE MATERIAL

NOVARTIS will destroy waste material in a secure, documented and legal manner,
preventing environmental problems and unauthorized use. Rejected packed product
and any rejected labeling and packaging components bearing IDENIX' name must be
defaced and/or incinerated.

                                                                             8/8

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

11   TERM AND EXPIRATION OF THE QA AGREEMENT

This agreement forms an integral part of the Packaging Agreement and shall come
to force and effect once signed by the parties hereto. The termination of this
agreement shall be in accordance with the Packaging Agreement.

12   DEFINITIONS

See Packaging Agreement

13   LIST OF ENCLOSURES

ENCLOSURE A:   List of QA/QC Liaisons

ENCLOSURE B:   Table of Responsibilities

ENCLOSURE C:   List of Products

ENCLOSURE E:   Directives, Manufacturing and Testing Documents

                                                                             9/9

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

14   SIGNATURE:

IDENIX PHARMACEUTICALS, INC.            NOVARTIS PHARMACEUTICALS CORPORATION

/s/ David Hallinan, PhD                 /s/ Johnny Mikell
-------------------------------------   ----------------------------------------
David Hallinan, PhD                     Johnny Mikell
Vice President Regulatory Affairs       Vice President PharmOps US QA

/s/ Leigh Boutilier                     /s/ Colin Bosch
-------------------------------------   ----------------------------------------
Leigh Boutilier                         Colin Bosch
Quality Assurance Specialist            Manager QA

                                                                           10/10
<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

ENCLOSURE A: LIST OF QA/QC LIAISONS

This enclosure shall be finalized before first delivery of packaged Product to
IDENIX. One key-account from the QA departments shall be nominated to act as
key-account to the other party.

                                     IDENIX

<TABLE>
<S>               <C>                 <C>
NAME              FUNCTION            ADDRESS
Leigh Boutilier   Quality Assurance   60 Hampshire Street
                                      Cambridge, MA 02139
</TABLE>

<TABLE>
<S>               <C>                 <C>
TELEPHONE         FAX                 E-MAIL
617-995-9916      TBD                 Boutilier.leigh@idenix.com
</TABLE>

                                    NOVARTIS

<TABLE>
<CAPTION>
FUNCTION                 NAME             DEPT.   TELEPHONE      EMAIL
--------                 ----             -----   ------------   -----
<S>                      <C>              <C>     <C>            <C>
VP Quality Assurance     Johnny Mikell      QA    845-368-6462   johnny.mikell@.novartis.com
Head of Compliance and
Documentation            Julie Sanchez*     QA    845-368-6292   Julie.sanchez@novartis.com
Batch Release            Kevin Lombardi     QA    845-368-6691   Kevin.Lombardi@novartis.com
Change Control           Veronica Grimm     QA    845-368-6475   Veronica.Grimm@novartis.com
Analytical Methods       Timothy Reilly     QC    845-368-6250   Timothy.Reilly@novartis.com
Stability                Shawn Wang         QC    845-368-6249   Shawn.Wang@novartis.com
Complaints Manager       Mary DeClerck      QA    845-368-6226   Mary.DeClerck@novartis.com
</TABLE>

Key Contact*

IDENIX PHARMACEUTICALS, INC.            NOVARTIS

/s/ Leigh Boutilier                     /s/ Colin Bosch
-------------------------------------   ----------------------------------------
Leigh Boutilier                         Colin Bosch
Quality Assurance Specialist            Manager QA

                                                                           11/11

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

ENCLOSURE B: TABLE OF RESPONSIBILITIES

I = IDENIX

N = NOVARTIS

<TABLE>
<S>                                                                         <C>   <C>
GENERAL
Compliance with the  applicable code/s of GMP and quality systems            I     N
Confidentiality agreement                                                    I     N
Inspection, audit, and approval of facilities and quality systems and        I
evaluation of NOVARTIS licensing compliance

DOCUMENTATION
Approval of master packaging and labeling instructions                             N
Preparation of master packaging and labeling instructions                          N
Specifications for other packaging components (used for transport)                 N
Specifications for primary packaging                                         I
Specifications for printed packaging materials                               I
Specifications for secondary packaging materials                             I
Supply of safety and disposal data regarding materials and processes               N
Validation of computer systems                                                     N
Inspection of transport documents                                                  N

PACKAGING
Artwork supply                                                               I
Coincidence with dossier                                                     I
Approve packaging instruction                                                      N
Proof reading of text                                                        I
Purchase of primary packaging materials                                            N
Purchase of printing materials for printed packaging                               N
Purchase of secondary packaging materials                                          N
Quality control and release of secondary packaging materials                       N
Quality control of primary packaging materials                                     N
Release of packaging instruction                                                   N
Release of primary packaging materials                                             N
Release of printing materials                                                      N
Validation of critical parts of the process

QUALITY ASSURANCE
Approval of change requests (relevant to registration)                       I
Approval to rework product                                                   I
Conduct recall                                                               I
Final assessment of complaints                                               I
</TABLE>

                                                                           12/12

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

<TABLE>
<S>                                                                         <C>   <C>
QUALITY ASSURANCE
Final release according GMP guidelines                                       I
Interfunctional evaluation of changes                                        I     N
Investigate requirement to recall product                                    I
Investigate technical customer complaints                                    I     N
Issue of Product Quality Review (Annual Product Review)                      I
Maintain customer complaint files                                            I
Preparation of change requests                                               I     N
Prepare and provide certificates of analysis, certificates of packaging            N
Provide reports regarding deviations or non-conformances during packaging          N
QA approval of process validation protocols and reports                            N
Recall of product                                                            I
Reference samples of finished packed product                                       N
Release of bulk product for packaging on behalf of responsible party (I)           N
Release of finished packed product for shipment                                    N
Reply to complaints                                                          I
Report to technical customer complaints                                      I
Responsibility for release of bulk product for packaging on behalf of        I     N
responisible party (I).
Retain records of packaging                                                        N
Retain records of packaging component testing                                      N
Retain samples of printed/unprinted packaging material                             N
Stability testing (FUST)                                                     I     N
</TABLE>

IDENIX PHARMACEUTICALS, INC.            NOVARTIS

/s/ Leigh Boutilier                     /s/ Colin Bosch
-------------------------------------   ----------------------------------------
Leigh Boutilier                         Colin Bosch
Quality Assurance                       Manager QA

                                                                           13/13
<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

ENCLOSURE C: LIST OF PRODUCTS

This enclosure is mandatory. It shall be finalized before first packaging
operation. The basis number is the link to the relevant documentation and is
intended to be the baseline for the change control procedure.

<TABLE>
<CAPTION>
BASIS NO   MATERIAL NO.   MATERIAL DESCRIPTION   ACCEPTOR'S NO.
--------   ------------   --------------------   --------------
<S>        <C>            <C>                    <C>
1234567       123456                                 654321
</TABLE>

IDENIX PHARMACEUTICALS, INC.            NOVARTIS

/s/ Leigh Boutilier                     /s/ Colin Bosch
-------------------------------------   ----------------------------------------
Leigh Boutilier                         Colin Bosch
Quality Assurance                       Manager QA

                                                                           14/14

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

ENCLOSURE D: DIRECTIVES, PACKAGING AND TESTING DOCUMENTS

This enclosure shall be finalized before first packaging of Bulk Product. The
references shall be in compliance with the marketing authorization and is
intended to be the baseline for the change control procedure.

PACKAGING COMPONENTS

<TABLE>
<CAPTION>
         NAME/MATERIAL
NO.   IDENTIFICATION NO.   PROCURED BY   TYPE OF DOCUMENT   DOCUMENT CODE   DATE OF ISSUE
---   ------------------   -----------   ----------------   -------------   -------------
<S>   <C>                  <C>           <C>                <C>             <C>
1     Name                 G
      (Ident.No.)
2     Name                 G
      (Ident.No.)
3                          A
4                          A
</TABLE>

T = Testing Monograph, P = Pharmacopoeia, O = other

PRODUCT QUALITY REVIEWS

<TABLE>
<CAPTION>
         NAME/PRODUCT
NO.   IDENTIFICATION NO.   DEADLINE FOR SUBMISSION OF DATA
---   ------------------   -------------------------------
<S>   <C>                  <C>
1
2
</TABLE>

                                                                           15/15

<PAGE>

QUALITY AGREEMENT ON PACKAGING AND TESTING

FOLLOW-UP STABILITY PROGRAM

This enclosure shall be finalized before first packaging of Bulk Product. The
references shall be in compliance with the marketing authorization and is
intended to be the baseline for the change control procedure.

<TABLE>
<CAPTION>
NO.   PRODUCT   PACK. TYPE   STORAGE               TESTING SCHEDULE
---   -------   ----------   -------   ---------------------------------------
<S>   <C>       <C>          <C>       <C>    <C>    <C>    <C>    <C>    <C>
                                       [**]   [**]   [**]   [**]   [**]   [**]
1                  [**]        [**]    [**]   [**]   [**]   [**]   [**]   [**]
2                  [**]        [**]    [**]   [**]   [**]   [**]   [**]   [**]
                   [**]        [**]    [**]   [**]   [**]   [**]   [**]   [**]
</TABLE>

[**]   [**]

----------

IDENIX PHARMACEUTICALS, INC.            NOVARTIS

/s/ Leigh Boutilier                     /s/ Colin Bosch
-------------------------------------   ----------------------------------------
Leigh Boutilier                         Colin Bosch
Quality Assurance                       Manager QA

                                                                           16/16<PAGE>

                                                                    EXHIBIT 10.3
                            FIRST AMENDMENT OF LEASE

      THIS FIRST AMENDMENT OF LEASE is made this 24th day of July, 2006, by and
between RB KENDALL FEE, LLC ("Landlord") and IDENIX PHARMACEUTICALS, INC.,
having a mailing address at One Kendall Square, Building 1400, Cambridge,
Massachusetts 02139 ("Tenant").

                                    RECITALS:

      A. Reference is made to an Indenture of Lease dated June 8, 2005 by and
between One Kendall Square Associates, LLC, the predecessor in title to
Landlord, and Tenant ( "Lease") demising approximately 36,513 s.f. of rentable
square feet of space on a portion of the first, fourth, fifth and penthouse
floors of Building No. 1400, One Kendall Square, Cambridge, Massachusetts.
Capitalized terms used but not defined herein shall have the same meaning as in
the Lease.

      B. Landlord and Tenant are the current holders, respectively, of the
lessor's and lessee's interests in the Lease.

      C. Landlord and Tenant now desire to amend the Lease as set forth herein.

      D. Capitalized terms not defined herein shall have the meanings set forth
in the Lease.

                                   AGREEMENTS:

      NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree
to amend the Lease as follows:

      1. As of the earlier of (i) the date Tenant's contractor delivers to
Landlord a certificate stating that Tenant's Expansion Work (as defined herein)
has been substantially completed in accordance with plans approved by Landlord,
with the exception of minor items of incomplete work and so-called "punchlist
items" or (ii) August 15, 2006 (the earlier to occur of (i) or (ii) being
hereinafter called the "Expansion Commencement Date"), Landlord hereby leases to
Tenant and Tenant hereby leases from Landlord approximately 5,233 rentable
square feet of additional floor area on the fourth (4th) floor the Building as
shown outlined in red on "Exhibit A" attached hereto and made a part hereof (the
"Expansion Premises"). Effective as of the Expansion Commencement Date, all
references in the Lease to the Premises shall be deemed to include the Expansion
Premises. At the written request of either Landlord or Tenant, the parties
shall, after the occurrence of the Expansion Commencment Date, execute a written
agreement confirming the Expansion Commencment Date and the date of expiration
of the term of the Lease.

      2. Effective as of the Expansion Commencement Date, in addition to the
rent paid by Tenant in accordance with Article 6 of the Lease, Tenant shall pay
additional base rent for the balance of the term for the Expansion Premises at
the rate of $138,674.50 per annum, payable in advance, in monthly installments
of $11,556.21 (the "Expansion Premises Rent").

      3. Effective as of the Expansion Commencement Date, Tenant's Proportionate
Building Share shall increase to 31.39% and Tenant's Proportionate Common Area
Share shall increase to 6.61%.

<PAGE>

      4. Except as may otherwise be expressly set forth in this Amendment,
Tenant shall take the Expansion Premises "as is", in the condition in which the
Expansion Premises are in as of the Expansion Commencement Date. Landlord shall
deliver the Expansion Premises with the HVAC system serving the premises in good
working order.

      5. Tenant will be performing all work to prepare the Expansion Premises
for Tenant's occupancy (the "Tenant's Expansion Work"). Landlord shall, in the
manner set forth herein, contribute up to One Hundred Four Thousand Six Hundred
and Sixty and 00/100 ($104,660.00) Dollars ("Landlord's Expansion Contribution")
towards the costs of completing construction of Tenant's Expansion Work
including design and engineering fees. All of the provisions relating to
Tenant's Work as set forth in Sections 4.2 (b), (c) and (d) of the Lease shall
apply to Landlord's Expansion Contribution and Tenant's Expansion Work except
that Landlord shall have no obligation to pay Landlord's Expansion Contribution
in respect of any requisition submitted more than four (4) months after the
Expansion Premises Commencement Date.

      6. Tenant's Expansion Work shall be performed in accordance with the
provisions of the Lease (including, without limitation, Articles 12 and 13
hereof). Landlord shall have no liability or responsibility for any claim,
injury or damage alleged to have been caused by the particular materials,
whether building standard or non-building standard, selected by Tenant in
connection with Tenant's Expansion Work.

      7. Subject to delay by causes beyond the reasonable control of Landlord or
caused by the action or inaction of Tenant, Tenant shall be granted access to
the Expansion Premises for the purposes of commencing and completing Tenant's
Expansion Work upon execution of this Amendment. The failure to have the
Expansion Premises available to Tenant by the date of this Amendment shall in no
way affect the validity of this Amendment or the obligations of Tenant hereunder
nor shall the same be construed in any way to extend the term of the Lease, and
Tenant shall not have any claim against Landlord, and Landlord shall have no
liability to Tenant, by reason thereof. It is specifically understood and agreed
that Landlord has no obligation and has made no promises to alter, remodel,
improve, renovate, repair, decorate or otherwise prepare the Expansion Premises
for Tenant's occupation or use. However, the Expansion Commencement Date shall
be delayed one day for each day of delay in the delivery of the Expansion
Premises by Landlord to Tenant.

      8. Prior to entering the Expansion Premises Tenant shall provide
certificates of insurance evidencing that the Expansion Premises are included
under the policies of insurance required under the Lease. Tenant shall
coordinate such entry with Landlord's building manager, and such entry shall be
made in compliance with all terms and conditions of this Amendment and the Rules
and Regulations then in effect for the Building. Such right of entry shall be
deemed a license from Landlord to Tenant, and any entry thereunder shall be at
the risk of Tenant.

      9. The Tenant may occupy and use the Expansion Premises only for general
business offices.

      10. The name and address of the Landlord on Exhibit 1, Sheet 1 is hereby
changed to: RB Kendall Fee, LLC, One Kendall Square, Cambridge, Massachusetts
02139. Any notices given to Landlord shall be delivered in accordance with the
terms of the Lease to the foregoing address with copies to be delivered in like
manner to Landlord, c/o The Beal Companies, LLP, 177 Milk Street, Boston,
Massachusetts, Attention: Stephen N. Faber, Vice President and to Sherin and
Lodgen, LLP, 101 Federal Street, Boston, Massachusetts 02110, Attention: Peter
A. Spellios, Esquire.

                                       2
<PAGE>

      11. Section 29.18 of the Lease is hereby amended to provide that as of the
Expansion Commencement Date, the Landlord shall make available to Tenant five
(5) additional monthly parking passes for use in the OKS Garage. The additional
passes shall be paid for by Tenant at the current prevailing rate in the OKS
Garage as such rate may vary as set forth in Section 29.18.

      12. Notwithstanding anything in the Lease to the contrary, Tenant shall,
for the period beginning June 1, 2006 and ending on May 31, 2007 (the "Storage
Space Term"), have the exclusive license to use the Storage Space (approximately
665 s.f.) in the basement of the Building as shown hatched on the plan attached
hereto as "Exhibit A-1" ("Storage Space"), for the storage of Tenant's personal
property and effects relating to its permitted use of the premises under the
Lease and for no other purpose(s). Tenant shall have no rights to extend or
renew the Storage Space Term. Except as otherwise provided herein, Tenant's use
of the Storage Space shall be subject to all of the terms and conditions of the
Lease. Tenant agrees to pay to Landlord, in advance and as additional rent under
the Lease without demand, offset or deduction, at the same time as monthly
installments of base rent are due under the Lease, a license fee equal to
$554.16 per month during each month of the Storage Space Term. In the event of
the termination or expiration of the Lease, Tenant's license to use the Storage
Space, if not already terminated or expired, shall immediately terminate without
any further notice or demand. Tenant agrees that it is taking the Storage Space
"as-is", in the condition in which the Storage Space is in as of the date
hereof, without any obligation on the part of Landlord to prepare or construct
the Storage Space for Tenant's occupancy and without any warranty or
representation by Landlord as to the condition of the Storage Space or its
fitness for any use or purpose. Tenant shall keep neat and clean and maintain in
good order, condition and repair, the Storage Space excepting only damage by
fire or other casualty or as a consequence of the exercise of the power of
eminent domain and reasonable wear and tear and Tenant shall surrender the
Storage Space at the expiration of the Storage Space Term, unless sooner
terminated, in such condition, free of all personal property and effects. Tenant
shall maintain and use the Storage Space in accordance with all Federal, State,
County and Municipal laws, rules, orders and regulations. Tenant acknowledges
and agrees that Landlord shall have no obligation to provide cleaning or other
services to the Storage Space. In addition to the other termination rights set
forth in the Lease, either party shall have the right to terminate this license
to use the Storage Space upon not less than one (1) month written notice to the
other party, and upon such termination Tenant shall surrender the Storage Space
as set forth above.

      13. The Landlord and Tenant each warrant and represent to the other that
they have dealt with no brokers in connection with the negotiation or
consummation of this Amendment other than Richard Barry Joyce & Partners and
Lincoln Property Company, and in the event of any brokerage claim against either
party by any person (other than the aforementioned brokers) claiming to have
dealt with either Landlord or Tenant in connection with this Amendment, the
party with whom such person claims to have dealt shall defend and indemnify the
other party against such claim. Any brokerage fees due Richard Barry Joyce &
Partners and Lincoln Property Company shall be the responsibility of Landlord
pursuant to separate agreements.

      14. In all other respects the Lease shall remain unmodified and shall
continue in full force and effect, as amended hereby. The parties hereby ratify,
confirm, and reaffirm all of the terms and conditions of the Lease, as amended
hereby.

                                       3
<PAGE>

IN WITNESS WHEREOF the parties hereto have executed this First Amendment of
Lease on the date first written above in multiple copies, each to be considered
an original hereof, as a sealed instrument.

LANDLORD:                                       TENANT:

RB KENDALL FEE, LLC,                            IDENIX
a Delaware limited liability company            PHARMACEUTICALS, INC.

By: RWB Kendall Square I, LLC,
    a Delaware limited liability company,
    its Sole Member

    By: RB Kendall, LLC,                       By: /s/ Jean-Pierre Sommadossi
        a Delaware limited liability company,     Name: Jean-Pierre Sommadossi
        its Sole Member                           Title: Chief Executive Officer
                                                        Hereunto duly authorized

         By:  Beal Kendall LLC,
              a Massachusetts limited
              liability company, as Manager

              By: /s/ Robert L. Beal
                 Name: Robert L. Beal
                 Title: Manager

                                       4
<PAGE>

                                    EXHIBIT A

                         PLAN SHOWING EXPANSION PREMISES

                                       5
<PAGE>

                                   EXHIBIT A-1

                           PLAN SHOWING STORAGE SPACE

                                       6

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00108-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00108-of-00352.parquet"}]]