EXHIBIT 10.2
                               [LIGAND LETTERHEAD}


8 December 2005

Tod Mertes
608 The Strand
Oceanside, CA  92054

Dear Tod:

                  The  purpose of this  letter  agreement  is to document 1) the
terms  of a  severance  package  to  which  you  will be  entitled  should  your
employment with Ligand  Pharmaceuticals  Incorporated (the "Company")  terminate
under certain specified  circumstances and 2) the terms of a stay bonus to which
you will become entitled under certain other circumstances.

                  DEFINITIONS.   For  purposes  of  this  letter  agreement  the
following definitions will be in effect:

               1. "Involuntary Termination" or "Involuntarily  Terminated" means
               the termination of your employment with the Company:

                        (i) upon your involuntary discharge or dismissal, or

                        (ii) upon your resignation in connection with any of the
               following changes to the terms and conditions of your employment:
               (A) a change in your position with the Company which materially
               reduces your level of responsibility, (B) a material reduction in
               your level of compensation (including base salary, fringe
               benefits and participation in non-discretionary bonus programs
               under which awards are payable pursuant to objective financial or
               performance standards, but excluding equity compensation) or (C)
               a relocation of your principal place of employment by more than
               fifty (50) miles.

               2. "Termination for Cause" means an Involuntary Termination
               or resignation of your employment with the Company by reason of
               your conviction of any felony or other criminal act, your
               commission of any act of fraud or embezzlement, your unauthorized
               use or disclosure of confidential or proprietary information or
               trade secrets of the Company or its subsidiaries, or any other
               intentional misconduct on your part which adversely affects the
               business or affairs of the Company in a material manner.

               INVOLUNTARY TERMINATION BENEFITS. In the event you are
               Involuntarily Terminated, other than a Termination for Cause, you
               will receive within 10 business days of such Involuntary
               Termination a lump-sum payment before taxes equal to twelve (12)
               months' refular salary



               as in effect at your termination date, PROVIDED you are not
               also entitled by reason of such Involuntary Termination to
               receive change of control severance benefits under the executive
               severance letter agreement between you and the Company dated May
               20, 2003 (or any successor agreement thereto).

               STAY BONUS. Provided that you are continuously employed by
               the Company and available for work (except normal holidays and
               approved paid time off) from the date of this letter, up to and
               including December 31, 2006, you will receive on or before
               January 31, 2007 a lump-sum payment before taxes equal to 4
               months' regular salary (the "Stay Bonus") as in effect on
               December 31, 2006. In the event of your Involuntary Termination
               in connection with a Change of Control (as defined in the
               executive severance letter agreement between you and the Company
               dated May 20, 2003 (or its successor)) prior to June 30, 2006,
               you will be entitled to receive within 10 business days of such
               Involuntary Termination, in addition to any benefits under such
               other agreement, one half of the Stay Bonus based on your salary
               as in effect at the date of such Involuntary Termination. In the
               event of your Involuntary Termination in connection with a Change
               of Control (as defined in the executive severance letter
               agreement between you and the Company dated May 20, 2003 (or its
               successor)) on or after June 30, 2006 up to and including
               December 31, 2006, you will be entitled to receive within 10
               business days of such Involuntary Termination, in addition to any
               benefits under such other agreement, the full Stay Bonus based on
               your salary as in effect at the date of such Involuntary
               Termination.


               MISCELLANEOUS PROVISIONS

               1. Entire Agreement; Amendments. This letter agreement sets
               forth the complete understanding of the parties with respect to
               the subject matter hereof and merges all prior communications,
               PROVIDED THAT, for clarity, this letter agreement is separate
               from and in addition to (a) that executive severance letter
               agreement between you and the Company dated May 20, 2003 (or any
               successor thereto) (b) your regular salary and annual bonus (c)
               your restatement completion bonus offer. No amendment of this
               letter agreement shall be effective unless in writing and signed
               by both parties.

               2. Term. This letter agreement shall expire on December 31, 2006.

               3. General Creditor Status. The benefits to which you may
               become entitled under this letter agreement will be paid, when
               due, from the general assets of the Company. Your right (or the
               right of the executors or administrators of your estate) to
               receive any such payments will at all times be that of a general
               creditor of the Company and will have no priority over the claims
               of other general creditors of the Company.

               4. Death. Should you die before receipt of all benefits to
               which you become entitled under this letter agreement, then the
               payment of such benefits will be made, on the due date or dates
               hereunder had you survived, to the executors or administrators of
               your estate.

               5. Miscellaneous. The provisions of this letter agreement
               will be construed and interpreted under ERISA. To the extent
               ERISA is inapplicable, then the laws of the State of California



               shall control, without regard to that state's choice of law
               provisions. If any provision of this letter agreement as applied
               to any party or to any circumstance should be adjudged by an
               arbitrator or court of competent jurisdiction to be void or
               unenforceable for any reason, the invalidity of that provision
               shall in no way affect (to the maximum extent permissible by law)
               the application of such provision under circumstances different
               from those so adjudicated, the application of any other provision
               of this letter agreement, or the enforceability or invalidity of
               this letter agreement as a whole. Should any provision of this
               letter agreement become or be determined to be invalid, illegal
               or unenforceable in any jurisdiction by reason of the scope,
               extent or duration of its coverage, then such provision shall be
               deemed amended to the extent necessary to conform to applicable
               law so as to be valid and enforceable or, if such provision
               cannot be so amended without materially altering the intention of
               the parties, then such provision shall be stricken and the
               remainder of this letter agreement shall continue in full force
               and effect.

               6. Section 409A Compliance. Notwithstanding anything to the
               contrary in this Agreement, the parties acknowledge and agree
               that any payment to be made, or benefit provided, pursuant to
               this Agreement shall be delayed if and to the extent necessary
               for this Agreement and such payment or benefit to comply with
               Section 409A of the Internal Revenue Code of 1986, as amended
               from time to time, and the Treasury Regulations and other
               interpretive guidance issued thereunder.

               7. Remedies. All rights and remedies provided pursuant to
               this letter agreement or by law will be cumulative, and no such
               right or remedy will be exclusive of any other. A party may
               pursue any one or more rights or remedies hereunder or may seek
               damages or specific performance in the event of another party's
               breach hereunder or may pursue any other remedy by law or equity,
               whether or not stated in this letter agreement.

               8. Arbitration. Any controversy which may arise between you
               and the Company with respect to the construction, interpretation
               or application of any of the terms, provisions or conditions of
               this letter agreement or any monetary claim arising from or
               relating to this letter agreement will be submitted to and
               exclusively decided by final and binding arbitration in San
               Diego, California in accordance with the rules of the American
               Arbitration Association then in effect.

               9. No Employment or Service Contract. Nothing in this letter
               agreement shall confer upon you any right to continue in the
               employment of the Company for any period of specific duration or
               interfere with or otherwise restrict in any way the rights of the
               Company or you, which rights are hereby expressly reserved by
               each, to terminate your employment at any time for any reason
               whatsoever, with or without cause.

               10. Proprietary Information. You hereby acknowledge that the
               Company may, from time to time during your employment with the
               Company, disclose to you confidential information pertaining to
               the Company's business and affairs. All information and data,
               whether or not in writing, of a private or confidential nature
               concerning the business or financial affairs of the Company is
               and will remain subject to a separate Proprietary Information and
               Inventions Agreement (or the like) between you and the Company.


                  Please indicate your acceptance of the foregoing provisions of
this severance  agreement by signing the enclosed copy of this letter  agreement
and returning it to the Company. This letter agreement is subject to approval by
the Compensation Committee,  and upon such approval shall be effective as of the
first date written above.

Very truly yours,

LIGAND PHARMACEUTICALS INCORPORATED

/s/ David E. Robinson

David E. Robinson
Chairman, President and CEO



ACCEPTED BY AND AGREED TO


Signature:  /s/ Tod G. Mertes


Dated:      12/13/05