WARRANT TO PURCHASE [____] SHARES OF COMMON STOCK

Exhibit 4.1 XENOPORT, INC.

WARRANT TO PURCHASE [____] SHARES OF COMMON STOCK Date of Issuance: [______] [__], 200__ VOID AFTER [______] [__], 200__       This Certifies That , for value received, [___], or permitted registered assigns (the " Holder "), is entitled to subscribe for and purchase at the Exercise Price (defined below) from XenoPort, Inc., a Delaware corporation (the " Company "), up to [___] shares of the common stock of the Company, par value $.001 per share (the " Common Stock "). This warrant is one of a series of warrants issued by the Company as of the date hereof (individually a " Warrant "; collectively, " Company Warrants ") pursuant to those certain purchase agreements between the Company and each of the Investors, each dated as of December 30, 2008 (each, a " Purchase Agreement ").       1. Definitions . Capitalized terms used herein but not otherwise defined herein shall have their respective meanings as set forth in the Purchase Agreement. As used herein, the following terms shall have the following respective meanings:            (A)  " Eligible Market " means any of the New York Stock Exchange, the American Stock Exchange, The NASDAQ Global Market, The NASDAQ Global Select Market or The NASDAQ Capital Market.            (B)  " Exercise Period " shall mean the period ending five years from the date hereof, unless sooner terminated as provided below.            (C)  " Exercise Price " shall mean $25.40 per share, subject to adjustment pursuant to Section 4 below.            (D)  " Exercise Shares " shall mean the shares of Common Stock issuable upon exercise of this Warrant.            (E)  " Fundamental Transaction " means that the Company shall, directly or indirectly, in one or more related transactions, (i) consolidate or merge with or into (whether or not the Company is the surviving corporation) another Person, or (ii) sell, assign, transfer, convey or otherwise dispose of all or substantially all of the properties or assets of the Company to another Person, or (iii) enter into an agreement with another Person pursuant to which such Person agrees to make a purchase, tender or exchange offer that is accepted by the holders of more than the 50% of the outstanding shares of Common Stock (not including any shares of Common Stock held by the Person or Persons making or party to, or associated or affiliated with the Persons making or party to, such purchase, tender or exchange offer), or (iv) consummate a stock purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another Person

whereby such other Person acquires more than the 50% of the outstanding shares of Common Stock (not including any shares of Common Stock held by the other Person or other Persons making or party to, or associated or affiliated with the other Persons making or party to, such stock purchase agreement or other business combination), (v) reorganize, recapitalize or reclassify its Common Stock, or (vi) any "person" or "group" (as these terms are used for purposes of Sections 13(d) and 14(d) of the Exchange Act) is or shall become the "beneficial owner" (as defined in Rule 13d-3 under the Exchange Act), directly or indirectly, of 50% of the aggregate ordinary voting power represented by issued and outstanding Common Stock.            (F)  " Parent Entity " of a Person means an entity that, directly or indirectly, controls the applicable Person and whose common stock or equivalent equity security is quoted or listed on The New York Stock Exchange, Inc. or an Eligible Market, or, if there is more than one such Person or Parent Entity, the Person or Parent Entity with the largest public market capitalization as of the date of consummation of the Fundamental Transaction.            (G)  " Person " means an individual, a limited liability company, a partnership, a joint venture, a corporation, a trust, an unincorporated organization, any other entity and a government or any department or agency thereof.            (H)  " Successor Entity " means the Person (or, if so elected by the Holder, the Parent Entity) formed by, resulting from or surviving any Fundamental Transaction or the Person (or, if so elected by the Holder, the Parent Entity) with which such Fundamental Transaction shall have been entered into.            (I)  " Trading Day " shall mean (a) any day on which the Common Stock is listed or quoted and traded on its primary Trading Market, (b) if the Common Stock is not then listed or quoted and traded on any Eligible Market, then a day on which trading occurs on the OTC Bulletin Board (or any successor thereto), or (c) if trading does not occur on the OTC Bulletin Board (or any successor thereto), any Business Day.            (J)  " Trading Market " shall mean the OTC Bulletin Board or any other Eligible Market, or any national securities exchange, market or trading or quotation facility on which the Common Stock is then listed or quoted.       2. Exercise of Warrant .            2.1 Exercise. The rights represented by this Warrant may be exercised in whole or in part at any time during the Exercise Period, by delivery of the following to the Company at its address set forth on the signature page hereto (or at such other address as it may designate by notice in writing to the Holder):            (A)  An executed Notice of Exercise in the form attached hereto;            (B)  Payment of the Exercise Price either (i) in cash or by check or (ii) pursuant to Section 2.2 below; and            (C)  This Warrant.

          Execution and delivery of the Notice of Exercise shall have the same effect as cancellation of the original Warrant and issuance of a new Warrant evidencing the right to purchase the remaining number of Exercise Shares, if any.      Certificates for shares purchased hereunder shall be transmitted by the transfer agent of the Company to the Holder by crediting the account of the Holder’s prime broker with the Depository Trust Company through its Deposit Withdrawal Agent Commission system if the Company is a participant in such system, and otherwise by physical delivery to the address specified by the Holder in the Notice of Exercise within three business days from the delivery to the Company of the Notice of Exercise, surrender of this Warrant and payment of the aggregate Exercise Price as set forth above. This Warrant shall be deemed to have been exercised on the date the Exercise Price is received by the Company.      The person in whose name any certificate or certificates for Exercise Shares are to be issued upon exercise of this Warrant shall be deemed to have become the holder of record of such shares on the date on which this Warrant was surrendered and payment of the Exercise Price was made, irrespective of the date of delivery of such certificate or certificates, except that, if the date of such surrender and payment is a date when the stock transfer books of the Company are closed, such person shall be deemed to have become the holder of such shares at the close of business on the next succeeding date on which the stock transfer books are open.      Subject to the final sentence of this paragraph and to the extent permitted by law, the Company’s obligations to issue and deliver Exercise Shares in accordance with the terms hereof are absolute and unconditional, irrespective of any action or inaction by the Holder to enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against any person or entity or any action to enforce the same, or any setoff, counterclaim, recoupment, limitation or termination, or any breach or alleged breach by the Holder or any other person or entity of any obligation to the Company or any violation or alleged violation of law by the Holder or any other person or entity, and irrespective of any other circumstance which might otherwise limit such obligation of the Company to the Holder in connection with the issuance of Exercise Shares. The Holder shall, subject to the following proviso, have the right to pursue any remedies available to it hereunder, at law or in equity including, without limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver Exercise Shares upon exercise of this Warrant as required pursuant to the terms hereof; provided , however , that notwithstanding anything to the contrary in this Warrant or in the Purchase Agreements, if the Company is for any reason unable to deliver Exercise Shares upon exercise of this Warrant as required pursuant to the terms hereof, the Company shall have no obligation to pay to the Holder any cash or other consideration or otherwise "net cash settle" this Warrant.      Except for cash in lieu of fractional shares as provided in Section 5, this Warrant may not be settled by the Company for cash to the Holder in lieu of Common Stock.            2.2 Net Exercise . If during the Exercise Period the fair market value of one share of the Common Stock is greater than the Exercise Price (at the date of calculation as set forth below), in lieu of exercising this Warrant by payment of cash or by check, the Holder may, at its election, effect a "net exercise" of this Warrant, in which event, if so effected, the Holder

shall receive Exercise Shares equal to the value (as determined below) of this Warrant (or the portion thereof being canceled) by surrender of this Warrant at the principal office of the Company, together with the properly endorsed Notice of Exercise, in which event the Company shall issue to the Holder a number of shares of Common Stock computed using the following formula: