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                                                                 EXHIBIT 10.63


                                FIRST AMENDMENT

                            TO EMPLOYMENT AGREEMENT

     This agreement amends the Employment Agreement originally made as of March
12, 2003 by and between Gen-Probe Incorporated, a Delaware corporation with
offices at 10210 Genetic Center Drive, San Diego, California 92121
("Gen-Probe"), and Henry L. Nordhoff (the "Executive"). This agreement
(hereafter referred to as the "First Amendment") is effective as of January 1,
2004, (the "Effective Date").

     WHEREAS, the Board of Directors of Gen-Probe (the "Board") has conducted
its regular annual review of Executive's performance and has reviewed the terms
of the Employment Agreement and desires to amend those terms; and

     WHEREAS, the Executive has considered and accepts the amendments proposed
by the Board.

     ACCORDINGLY, Gen-Probe and Executive agree to amend the original
Employment Agreement as follows:

     1.  Section 3(a)("Salary") shall be and is hereby amended to state that
beginning January 1, 2004 and continuing throughout the period of Executive's
employment, Executive's current salary shall be and is hereby increased by
$36,400 and Gen-Probe shall pay Executive an annual base salary of $511,400.00.
This base salary may be increased by the Board, subject to the terms of this
Agreement and consistent with the Executive's performance and Gen-Probe's
policy regarding adjustments in officer compensation established from time to
time by the Board. The base salary shall not be decreased during the term of
this Agreement.

     2.  Section 3(c)("Stock Options/Restricted Stock") shall be amended to
reflect the 2-for-1 stock split by share dividend that took place on September
30, 2003. Therefore Section 3(c) shall be and is hereby amended to state that
not later than June 30 during each year of the term of the amended Agreement,
the Executive will be awarded not less than 20,000 restricted shares and not
less than 100,000 options of Gen-Probe common stock, if such options or
restricted shares are then available under an equity participation plan adopted
by Gen-Probe.

     3.  Section 3(g)("Clubs") shall be and is hereby amended to permanently
terminate Gen-Probe's obligation to pay Executive's membership dues to the
Fairbanks Ranch Country Club. Executive shall own all right, title and interest
in the membership in Fairbanks Ranch Country Club, free of any claim by
Gen-Probe.

     4.  Except as expressly set forth in this First Amendment, all terms and
conditions of the original Employment Agreement, dated March 12, 2003, are
hereby ratified and shall continue in full force and effect.



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     In witness whereof, the parties have executed this Agreement.



Executive:                              Gen-Probe Incorporated:


/s/ Henry L. Nordhoff                  By /s/ Robin L. Vedova
----------------------------           ------------------------------------
    Henry L. Nordhoff                       Robin L. Vedova
                                        Vice President, Administration


                                        By /s/ R. William Bowen
                                        -----------------------------------
                                             R. William Bowen
                                         Vice President and General Counsel






























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