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                                                                   EXHIBIT 10.71

                             GEN-PROBE INCORPORATED

                          EMPLOYEE STOCK PURCHASE PLAN
             (adopted by Board of Directors on May 3, 2003 and the
                    Compensation Committee on April 2, 2003)
           (amended by the Compensation Committee on August 2, 2004)
                   (adopted by Stockholders on May 29, 2003)

            Gen-Probe Incorporated, a Delaware corporation (the "Company"),
hereby adopts the Gen-Probe Incorporated Employee Stock Purchase Plan (the
"Plan"), effective as of May 30, 2003.

            The purposes of the Plan are as follows:

                  (1) To assist eligible employees of the Company and its
      Designated Subsidiary Corporations (as defined below) in acquiring stock
      ownership in the Company pursuant to a plan which is intended to qualify
      as an "employee stock purchase plan," within the meaning of Section 423(b)
      of the Code (as defined below).

                  (2) To encourage such employees to remain in the employment of
      the Company and its Subsidiary Corporations.

      1. DEFINITIONS. Whenever any of the following terms is used in the Plan
with the first letter or letters capitalized, it shall have the following
meaning unless context clearly indicates to the contrary (such definitions to be
equally applicable to both the singular and the plural forms of the terms
defined):

            (a) "Account" shall mean the account established for an Eligible
Employee under the Plan with respect to an Offering Period.

            (b) "Agent" shall mean the brokerage firm, bank or other financial
institution, entity or person(s) engaged, retained, appointed or authorized to
act as the agent of the Company or an Employee with regard to the Plan.

            (c) "Authorization" shall mean an Eligible Employee's payroll
deduction authorization with respect to an Offering Period provided by such
Eligible Employee in accordance with Section 3(b).

            (d) "Base Compensation" shall mean the (i) base salary payable to an
Eligible Employee by the Company during such individual's period of
participation in one or more Offering Periods under the Plan, plus (ii) all
overtime payments, bonuses, commissions, current profit-sharing distributions
and other incentive compensation payments. Such Base Compensation shall be
calculated before deduction of (A) any income or employment tax withholdings, or
(B) any pre-tax contributions made by the Company to any Code Section 401(k)
salary deferral plan or any Code Section 125 cafeteria benefit program now or
hereafter established by the Company. However, Base Compensation shall not
include any contributions (other than Code Section 401(k) or Code Section 125
contributions) made on the Eligible Employee's behalf by the Company to any
employee benefit or welfare plan now or hereafter established.

            (e) "Board" means the Board of Directors of the Company.

            (f) "Code" means the Internal Revenue Code of 1986, as amended.

            (g) "Committee" means the committee of the Board appointed to
administer the Plan pursuant to Section 13.

            (h) "Company" means Gen-Probe Incorporated, a Delaware corporation.

            (i) "Date of Exercise" of any Option means the date on which such
Option is exercised, which shall be the last day of the Offering Period with
respect to which the Option was granted, in accordance with Section 4(a) (except
as provided in Section 9).
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            (j) "Date of Grant" of any Option means the date on which such
Option is granted, which shall be the first day of the Offering Period with
respect to which the Option was granted, in accordance with Section 3(a).

            (k) "Designated Subsidiary Corporation" means any Subsidiary
Corporation designated by the Board in accordance with Section 14.

            (l) "Eligible Employee" means an Employee of the Company or any
Designated Subsidiary Corporation who does not, immediately after the Option is
granted, own (directly or through attribution) stock possessing five percent
(5%) or more of the total combined voting power or value of all classes of Stock
or other stock of the Company, a Parent Corporation or a Subsidiary Corporation
(as determined under Section 423(b)(3) of the Code). The rules of Section 424(d)
of the Code with regard to the attribution of stock ownership shall apply in
determining the stock ownership of an individual, and stock that an Employee may
purchase under outstanding options shall be treated as stock owned by the
Employee. During a leave of absence meeting the requirements of Treasury
Regulation Section 1.421-7(h)(2), an individual shall be treated as an Employee
of the Company or Subsidiary Corporation employing such individual immediately
prior to such leave. Notwithstanding the foregoing, an Employee whose customary
employment is for 20 hours or less per week or for less than 5 months in any
calendar year shall not be Eligible an Employee.

            (m) "Employee" shall mean an individual who renders services to the
Company or a Subsidiary Corporation in the status of an "employee" within the
meaning of Code Section 3401(c). "Employee" shall not include any director of
the Company or a Subsidiary Corporation who does not render services to the
Company or a Subsidiary Corporation in the status of an "employee" within the
meaning of Code Section 3401(c).

            (n) "Offering Period" shall mean, effective September 1, 2004, each
six-month period commencing on any January 1 and July 1; provided, however, that
there shall be an Offering Period under the Plan commencing on September 1, 2004
and ending on the last trading day on or before December 31, 2004. Options shall
be granted on the Date of Grant and exercised on the Date of Exercise, as
provided in Sections 3(a) and 4(a), respectively.

            (o) "Option" means an option to purchase shares of Stock granted
under the Plan to an Eligible Employee in accordance with Section 3(a).

            (p) "Option Price" means the option price per share of Stock
determined in accordance with Section 4(b).

            (q) "Parent Corporation" means any corporation, other than the
Company, in an unbroken chain of corporations ending with the Company if, at the
time of the granting of the Option, each of the corporations other than the
Company owns stock possessing 50% or more of the total combined voting power of
all classes of stock in one of the other corporations in such chain.

            (r) "Payday" means the regular and recurring established day for
payment of Base Compensation to an Employee of the Company or any Subsidiary
Corporation.

            (s) "Plan" means the Gen-Probe Incorporated Employee Stock Purchase
Plan.

            (t) "Stock" means the shares of the Company's common stock, $0.0001
par value.

            (u) "Subsidiary Corporation" means any corporation, other than the
Company, in an unbroken chain of corporations beginning with the Company if, at
the time of the granting of the Option, each of the corporations other than the
last corporation in an unbroken chain owns stock possessing 50% or more of the
total combined voting power of all classes of stock in one of the other
corporations in such chain.

      2. STOCK SUBJECT TO THE PLAN. Subject to the provisions of Section 9
hereof (relating to adjustments upon changes in the Stock) and Section 12 hereof
(relating to amendments of the Plan), the

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maximum number of shares of Stock which shall be made available for sale under
the Plan shall be 1,000,000(1) shares.

      3. GRANT OF OPTIONS.

            (a) Option Grants. The Company shall grant Options under the Plan to
all Eligible Employees in successive Offering Periods until the earlier of: (i)
the date on which the number of shares of Stock available under the Plan have
been sold or (ii) the date on which the Plan is suspended or terminates. Each
Employee who is an Eligible Employee on the first day of an Offering Period
shall be granted an Option with respect to such Offering Period. The Date of
Grant of such an Option shall be the first day of the Offering Period with
respect to which such Option was granted. Each Option shall expire on the Date
of Exercise immediately after the automatic exercise of the Option in accordance
with Section 4(a), unless such Option terminates earlier in accordance with
Section 5, 6 or 9. The number of shares of Stock subject to an Eligible
Employee's Option shall equal the cumulative payroll deductions authorized by
such Eligible Employee in accordance with subsection (b) of this Section 3 for
the Option Period (if any), divided by the Option Price; provided, however, that
the number of shares of Stock subject to such Option shall not exceed 200,000(2)
shares; and, provided, further, that the number of shares of Stock subject to
such Option shall not exceed the number determined in accordance with subsection
(c). The Company shall not grant an Option with respect to an Offering Period to
any individual who is not an Eligible Employee on the first day of such Offering
Period.

            (b) Election to Participate; Payroll Deduction Authorization. Except
as provided in subsection (d), an Eligible Employee shall participate in the
Plan only by means of payroll deduction. Each Eligible Employee who elects to
participate in the Plan with respect to an Offering Period shall deliver to the
Company, not later than ten (10) days before the first day of the Offering
Period, a completed and executed written payroll deduction authorization in a
form prepared by the Committee (the "Authorization"). An Eligible Employee's
Authorization shall give notice of such Eligible Employee's election to
participate in the Plan for the next following Offering Period (and subsequent
Offering Periods) and shall designate a whole percentage of such Eligible
Employee's Base Compensation to be withheld by the Company or the Designated
Subsidiary Corporation employing such Eligible Employee on each Payday during
the Offering Period. An Eligible Employee may designate any whole percentage of
Base Compensation which is not to be less than one percent (1%) and not more
than fifteen percent (15%). An Eligible Employee's Base Compensation payable
during an Offering Period shall be reduced each Payday through payroll deduction
in an amount equal to the percentage specified in the Authorization, and such
amount shall be credited to such Eligible Employee's Account under the Plan. An
Eligible Employee may change the percentage of Base Compensation designated in
the Authorization, subject to the limits of this subsection (b), or may suspend
the Authorization, at any time during the Offering Period, provided, that any
such change or suspension shall become effective not later than ten (10) days
after receipt by the Company. Any Authorization shall remain in effect for each
subsequent Offering Period, unless the Eligible Employee submits a new
Authorization pursuant to this subsection (b), withdraws from the Plan pursuant
to Section 5, ceases to be an Eligible Employee as defined in Section 1(l) or
terminates employment as provided in Section 6.

            (c) $25,000 Limitation. No Eligible Employee shall be granted an
Option under the Plan which permits his or her rights to purchase shares of
Stock under the Plan, together with other options to purchase shares of Stock or
other stock under all other employee stock purchase plans of the Company, any
Parent Corporation or any Subsidiary Corporation subject to Section 423 of the
Code, to accrue at a rate which exceeds $25,000 of fair market value of such
shares of Stock or other stock (determined at the time the Option or other
option is granted) for each calendar year in which the Option is outstanding at
any time. For purpose of the limitation imposed by this subsection, (i) the
right to purchase shares of Stock or other stock under an Option or other option
accrues when the Option or other option (or any portion thereof) first becomes
exercisable during the calendar year, (ii) the right to purchase shares of

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(1) Adjusted from 500,000 to 1,000,000 to reflect the two-for-one stock split
implemented as a 100% stock dividend, effective September 2003.

(2) Adjusted from 100,000 to 200,000 to reflect the two-for-one stock split
implemented as a 100% stock dividend, effective September 2003.

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Stock or other stock under an Option or other option accrues at the rate
provided in the Option or other option, but in no case may such rate exceed
$25,000 of the fair market value of such Stock or other stock (determined at the
time such Option or other option is granted) for any one calendar year, and
(iii) a right to purchase Stock or other stock which has accrued under an Option
or other option may not be carried over to any Option or other option. This
limitation shall be applied in accordance with Section 423(b)(8) of the Code and
the Treasury Regulations thereunder.

            (d) Leaves of Absence. During a leave of absence meeting the
requirements of Treasury Regulation Section 1.421-7(h)(2), an Employee may
continue to participate in the Plan by making cash payments to the Company on
each Payday equal to the amount of the Employee's payroll deduction under the
Plan for the Payday immediately preceding the first day of such Employee's leave
of absence.

      4. EXERCISE OF OPTIONS; OPTION PRICE.

            (a) Option Exercise. Each Employee automatically and without any act
on such Employee's part shall be deemed to have exercised such Employee's Option
on the Date of Exercise to the extent that the balance then in the Employee's
Account is sufficient to purchase, at the Option Price, shares of the Stock
subject to the Option. No fractional shares may be purchased upon exercise of
the Option. The balance of the amount credited to the Account of each Employee
that has not been applied to the purchase of shares of Stock on the Date of
Exercise as a result of the prohibition on the purchase of fractional shares
under the Plan shall remain in such Account and shall be applied to subsequent
Option exercises, subject to the terms of Sections 4(d) and 5(a). If any
additional amount remains credited to the Account of an Employee following the
exercise of the Option, the Company or Subsidiary Corporation employing the
Employee shall immediately pay to the Employee the amount credited to the
Employee's Account in one lump sum payment in cash, without any interest
thereon.

            (b) Option Price Defined. The option price per share of Stock (the
"Option Price") to be paid by an Employee upon the exercise of the Employee's
Option shall be equal to 85% of the lesser of: (i) the Fair Market Value of a
share of Stock on the Date of Exercise and (ii) the Fair Market Value of a share
of Stock on the Date of Grant. The "Fair Market Value" of a share of Stock as of
a given date shall be (a) the closing price of a share of Stock on the principal
stock exchange or the Nasdaq National Market or Nasdaq SmallCap Market on which
shares of Stock are then outstanding, if any (or as reported on any composite
index which includes such principal stock exchange or Nasdaq Market), on the
trading day previous to such date, or if shares were not traded on the trading
day previous to such date, then on the immediately preceding date on which a
trade occurred, (b) if Stock is not traded on an exchange or Nasdaq but is
quoted on a quotation system other than Nasdaq, the mean between the closing
representative bid and asked prices for the Stock on the trading day previous to
such date as reported by such quotation system, or (c) if Stock is not publicly
traded on an exchange or Nasdaq and not quoted on a quotation system other than
Nasdaq, the Fair Market Value of a share of Stock as established by the
Committee acting in good faith.

            (c) Book Entry/Share Certificates. As soon as reasonably practicable
after the purchase of whole shares of Stock upon the exercise of an Option by an
Employee, the Company shall issue the shares of Stock to such Employee and such
shares shall be held in the custody of the Agent for the benefit of the
Employee. The Company or the Agent shall make an entry on its books and records
indicating that the shares of Stock purchased in connection with such exercise
have been duly issued as of that date to such Employee. An Employee shall have
the right at any time to request in writing a certificate or certificates for
all or a portion of the whole shares of Stock purchased hereunder. Upon receipt
of an Employee's written request for any such certificate, the Company shall (or
shall cause the Agent to), within ten (10) days or, if later, as soon as
reasonably practicable after the date of such receipt, deliver any such
certificate to the Employee. Nothing in this subsection (c) shall prohibit the
sale or other disposition by an Employee of shares of Stock purchased hereunder.
In the event the Company is required to obtain authority from any commission or
agency to issue any certificate or certificates for all or a portion of the
whole shares of Stock purchased hereunder, the Company shall seek to obtain such
authority as soon as reasonably practicable.

            (d) Pro Rata Allocations. If the total number of shares of Stock for
which Options are to be exercised on any date exceeds the number of shares of
Stock remaining unsold under the Plan (after deduction for all shares of Stock
for which Options have theretofore been exercised), the Committee shall

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make a pro rata allocation of the available remaining shares of Stock in as
nearly a uniform manner as shall be practicable and the balance of the amount
credited to the Account of each Employee which has not been applied to the
purchase of shares of Stock shall be paid to such Employee in one lump sum in
cash within thirty (30) days after the Date of Exercise, without any interest
thereon.

            (e) Information Statement. The Company shall provide each Employee
whose Option is exercised with an information statement in accordance with
Section 6039(a) of the Code and the Treasury Regulations thereunder. The Company
shall maintain a procedure for identifying certificates of shares of Stock sold
upon the exercise of Options in accordance with Section 6039(b) of the Code.

      5. WITHDRAWAL FROM THE PLAN.

            (a) Withdrawal Election. An Employee may withdraw from participation
under the Plan at any time, except that an Employee may not withdraw during the
last ten (10) days of any Option Period. An Employee electing to withdraw from
the Plan must deliver to the Company a notice of withdrawal in a form prepared
by the Committee (the "Withdrawal Election") not later than ten (10) days prior
to the Date of Exercise for such Option Period. Upon receipt of an Employee's
Withdrawal Election, the Company or Subsidiary Corporation employing the
Employee shall pay to the Employee the amount credited to the Employee's Account
in one lump sum payment in cash, without any interest thereon, and subject to
Section 4(c), at the Employee's request the Company shall (or shall cause the
Agent to) deliver to the Employee certificates for any whole shares of Stock
previously purchased by the Employee (the value of any fractional share to be
returned to such Employee by check), in either case within thirty (30) days of
receipt of the Employee's Withdrawal Election. Upon receipt of an Employee's
Withdrawal Election by the Company, the Employee shall cease to participate in
the Plan and the Employee's Option for such Option Period shall terminate.

            (b) Eligibility following Withdrawal. An Employee who withdraws from
the Plan with respect to an Option Period, and who is still an Eligible
Employee, may elect to participate again in the Plan for any subsequent Offering
Period by delivering to the Company an Authorization not later than ten (10)
days before the first day of the Offering Period pursuant to Section 3(b).

      6. TERMINATION OF EMPLOYMENT.

            (a) Termination of Employment Other than by Death. If the employment
of an Employee with the Company and the Subsidiary Corporation terminates other
than by death, the Employee's participation in the Plan automatically and
without any act on the Employee's part shall terminate as of the date of the
termination of the Employee's employment. As soon as practicable after such a
termination of employment, the Company or Subsidiary Corporation employing the
Employee shall pay to the Employee the amount credited to the Employee's Account
in one lump sum payment in cash, without any interest thereon, and subject to
Section 4(c), at the Employee's request the Company shall (or shall cause the
Agent to) deliver to the Employee certificates for any whole shares of Stock
previously purchased by the Employee (the value of any fractional share to be
returned to such Employee by check). Upon an Employee's termination of
employment covered by this subsection, the Employee's Authorization and Option
under the Plan shall terminate.

            (b) Termination by Death. If the employment of an Employee is
terminated by the Employee's death, the executor of the Employee's will or the
administrator of the Employee's estate, by written notice to the Company, may
request payment of the balance in the Employee's Account, in which event the
Company or Subsidiary Corporation employing the Employee shall pay the amount
credited to the Employee's Account in one lump sum payment in cash, without any
interest thereon, and subject to Section 4(c), at the Employee's request the
Company shall (or shall cause the Agent to) deliver to the Employee certificates
for any whole shares of Stock previously purchased by the Employee (the value of
any fractional share to be returned to such Employee by check) as soon as
practicable after receiving such notice. Upon receipt of such notice, the
Employee's Authorization and Option under the Plan shall terminate. If the
Company does not receive such notice prior to the next Date of Exercise, the
Employee's Option shall be deemed to have been exercised on such Date of
Exercise.

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      7. RESTRICTION UPON ASSIGNMENT. An Option granted under the Plan shall not
be transferable other than by will or the laws of descent and distribution, and
is exercisable during the Employee's lifetime only by the Employee. Except as
provided in Section 6(b) hereof, an Option may not be exercised to any extent
except by the Employee. The Company shall not recognize and shall be under no
duty to recognize any assignment or alienation of the Employee's interest in the
Plan, the Employee's Option or any rights under the Employee's Option.

      8. NO RIGHTS OF STOCKHOLDERS UNTIL SHARES ISSUED. With respect to shares
of Stock subject to an Option, an Employee shall not be deemed to be a
stockholder of the Company, and the Employee shall not have any of the rights or
privileges of a stockholder, until such shares have been issued to the Employee
or his or her nominee following exercise of the Employee's Option. No
adjustments shall be made for dividends (ordinary or extraordinary, whether in
cash securities, or other property) or distribution or other rights for which
the record date occurs prior to the date of such issuance, except as otherwise
expressly provided herein.

      9. CHANGES IN THE STOCK AND CORPORATE EVENTS; ADJUSTMENT OF OPTIONS.

            (a) Subject to Section 9(c), in the event that the Committee, in its
sole discretion, determines that any dividend or other distribution (whether in
the form of cash, Stock, other securities, or other property), recapitalization,
reclassification, stock split, reverse stock split, reorganization, merger,
consolidation, split-up, spin-off, combination, repurchase, liquidation,
dissolution, or sale, transfer, exchange or other disposition of all or
substantially all of the assets of the Company, or exchange of Stock or other
securities of the Company, issuance of warrants or other rights to purchase
Stock or other securities of the Company, or other similar corporate transaction
or event, affects the Stock such that an adjustment is appropriate in order to
prevent dilution or enlargement of the benefits or potential benefits intended
to be made available under the Plan or with respect to an Option, then the
Committee shall, in such manner as it may deem equitable, adjust any or all of:

                  (i) the number and kind of shares of Stock (or other
      securities or property) with respect to which Options may be granted
      (including, but not limited to, adjustments of the limitation in Section
      3(a) on the maximum number of shares of Stock which may be purchased),

                  (ii) the number and kind of shares of Stock (or other
      securities or property) subject to outstanding Options, and

                  (iii) the exercise price with respect to any Option.

            (b) Subject to Section 9(c), in the event of any transaction or
event described in Section 9(a) or any unusual or nonrecurring transactions or
events affecting the Company, any affiliate of the Company, or the financial
statements of the Company or any affiliate, or of changes in applicable laws,
regulations, or accounting principles, the Committee, in its sole discretion,
and on such terms and conditions as it deems appropriate, either by the terms of
the Option or by action taken prior to the occurrence of such transaction or
event and either automatically or upon the Employee's request, is hereby
authorized to take any one or more of the following actions whenever the
Committee determines that such action is appropriate in order to prevent
dilution or enlargement of the benefits or potential benefits intended to be
made available under the Plan or with respect to any Option under the Plan, to
facilitate such transactions or events or to give effect to such changes in
laws, regulations or principles:

                  (i) To provide that all Options outstanding shall terminate
      without being exercised on such date as the Committee determines in its
      sole discretion;

                  (ii) To provide that all Options outstanding shall be
      exercised prior to the Date of Exercise of such Options on such date as
      the Committee determines in its sole discretion and such Options shall
      terminate immediately after such exercises.

                  (iii) To provide for either the purchase of any Option
      outstanding for an amount of cash equal to the amount that could have been
      obtained upon the exercise of such Option

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      had such Option been currently exercisable, or the replacement of such
      Option with other rights or property selected by the Committee in its sole
      discretion;

                  (iv) To provide that such Option be assumed by the successor
      or survivor corporation, or a parent or subsidiary thereof, or shall be
      substituted for by similar options, covering the stock of the successor or
      survivor corporation, or a parent or subsidiary thereof, with appropriate
      adjustments as to the number and kind of shares and prices; and

                  (v) To make adjustments in the number and type of shares of
      Stock (or other securities or property) subject to outstanding Options, or
      in the terms and conditions of outstanding Options, or Options which may
      be granted in the future.

            (c) No adjustment or action described in this Section 9 or in any
other provision of the Plan shall be authorized to the extent that such
adjustment or action would cause the Plan to fail to satisfy the requirements of
Section 423 of the Code. Furthermore, no such adjustment or action shall be
authorized to the extent such adjustment or action would result in short-swing
profits liability under Section 16 of the Securities and Exchange Act of 1934,
as amended, or violate the exemptive conditions of Rule 16b-3 unless the
Committee determines that the Option is not to comply with such exemptive
conditions. The number of shares of Stock subject to any Option shall always be
rounded to the next whole number.

            (d) The existence of the Plan and the Options granted hereunder
shall not affect or restrict in any way the right or power of the Company or the
stockholders of the Company to make or authorize any adjustment,
recapitalization, reorganization or other change in the Company's capital
structure or its business, any merger or consolidation of the Company, any issue
of stock or of options, warrants or rights to purchase stock or of bonds,
debentures, preferred or prior preference stocks whose rights are superior to or
affect the Stock or the rights thereof of which are convertible into or
exchangeable for Stock, or the dissolution or liquidation of the company, or any
sale or transfer of all or any part of its assets or business, or any other
corporate act or proceeding, whether of a similar character or otherwise.

      10. USE OF FUNDS; NO INTEREST PAID. All funds received or held by the
Company under the Plan shall be included in the general funds of the Company
free of any trust or other restriction and may be used for any corporate
purpose. No interest will be paid to any Employee or credited to any Employee's
Account with respect to such funds.

      11. DIVIDENDS.

            (a) Cash dividends and other cash distributions received by the
Agent with respect to Stock held in its custody hereunder will be credited to
each Employee's Account in accordance with such Employee's interests in such
Stock, and shall be applied, as soon as practicable after the receipt thereof by
the Agent, to the purchase in the open market at prevailing market prices of the
number of whole shares of Stock that may be purchased with such funds (after
deductions of any bank service fees, brokerage charges, transfer taxes, and any
other transaction fee, expense or cost payable in connection with the purchase
of such shares of Stock and not otherwise paid by the Employer.)

            (b) All purchases of shares of Stock made pursuant to this Section
11 will be made in the name of the Agent or its nominee, and shall be
transferred and credited to the Account(s) of the Employees to which such
dividends or other distributions were credited. Dividends paid in the form of
shares of Stock will be allocated by the Agent, as and when received, with
respect to Stock held in its custody hereunder to the Account of each Employee
in accordance with such Employee's interests in such Stock. Property, other than
Stock or cash, received by the Agent as a distribution on Stock held in its
custody hereunder, shall be sold by the Agent for the accounts of Employees, and
the Agent shall treat the proceeds of such sale in the same manner as cash
dividends received by the Agent on Stock held in its custody hereunder.

      12. AMENDMENT, SUSPENSION OR TERMINATION OF THE PLAN. Each of the Board
and the Committee may amend, suspend, or terminate the Plan at any time and from
time to time, including with

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respect to the duration or frequency of Offering Periods under the Plan,
provided that approval by a vote of the holders of the outstanding shares of the
Company's capital stock entitled to vote shall be required to amend the Plan to:
(a) change the number of shares of Stock that may be sold pursuant to Options
under the Plan, (b) alter the requirements for eligibility to participate in the
Plan, or (c) in any manner that would cause the Plan to no longer be an
"employee stock purchase plan" within the meaning of Section 423(b) of the Code.

      13. ADMINISTRATION BY COMMITTEE; RULES AND REGULATIONS.

            (a) Appointment of Committee. The Committee shall consist of two or
more members, and may be comprised of members of the Board or Employees.
Appointment of Committee members shall be made by the Board and shall be
effective upon acceptance of appointment. Committee members may resign at any
time by delivering written notice to the Board. Vacancies in the Committee may
be filled by the Board.

            (b) Duties and Powers of Committee. It shall be the duty of the
Committee to conduct the general administration of the Plan in accordance with
its provisions. The Committee shall have the power to interpret the Plan and the
terms of the Options, and to adopt such rules for the administration,
interpretation and application of the Plan as are consistent therewith and to
interpret, amend or revoke any such rules. In its absolute discretion, the Board
may at any time and from time to time exercise any and all rights and duties of
the Committee under the Plan.

            (c) Majority Rule; Unanimous Written Consent. The Committee shall
act by a majority of its members in attendance at a meeting at which a quorum is
present or by a memorandum or other written instrument signed by all members of
the Committee.

            (d) Compensation; Professional Assistance; Good Faith Actions.
Members of the Committee shall receive such compensation, if any, for their
services as members as may be determined by the Board. All expenses and
liabilities that members of the Committee incur in connection with the
administration of the Plan shall be borne by the Company. The Committee may,
with the approval of the Board, employ attorneys, consultants, accountants,
appraisers, brokers or other persons. The Committee, the Company and the
Company's officers and Directors shall be entitled to rely upon the advice,
opinions or valuations of any such persons. All actions taken and all
interpretations and determinations made by the Committee or the Board in good
faith shall be final and binding upon all Option holders, the Company and all
other interested persons. No members of the Committee or Board shall be
personally liable for any action, determination or interpretation made in good
faith with respect to the Plan or Options, and all members of the Committee and
the Board shall be fully protected by the Company to the maximum extent
permitted under applicable law and the charter documents of the Company in
respect of any such action, determination or interpretation.

      14. DESIGNATION OF SUBSIDIARY CORPORATIONS. The Board shall designate from
among the Subsidiary Corporations, as determined from time to time, the
Subsidiary Corporation or Subsidiary Corporations whose Employees shall be
eligible to be granted Options under the Plan. The Board may designate a
Subsidiary Corporation, or terminate the designation of a Subsidiary
Corporation, without the approval of the stockholders of the Company.

      15. NO RIGHTS AS AN EMPLOYEE. Nothing in the Plan shall be construed to
give any person (including any Eligible Employee) the right to remain in the
employ of the Company, a Parent Corporation or a Subsidiary Corporation or to
affect the right of the Company, any Parent Corporation or any Subsidiary
Corporation to terminate the employment of any person (including any Eligible
Employee) at any time, with or without cause.

      16. TERM; APPROVAL BY STOCKHOLDERS. Subject to approval by the
stockholders of the Company in accordance with this Section, the Plan shall
remain in effect until terminated in accordance with Section 12. No Option may
be granted during any period of suspension of the Plan or after termination of
the Plan. The Plan shall be submitted for the approval of the Company's
stockholders within twelve (12) months after the date of the adoption of the
Plan by the Board. Options may be granted prior to such stockholder approval;
provided, however, that such Options shall not be exercisable

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prior to the time when the Plan is approved by the Company's stockholders; and,
provided, further, that if such approval has not been obtained by the end of
said 12-month period, all Options previously granted under the Plan shall
thereupon terminate without being exercised.

      17. EFFECT UPON OTHER PLANS. The adoption of the Plan shall not affect any
other compensation or incentive plans in effect for the Company, any Parent
Corporation or any Subsidiary Corporation. Nothing in this Plan shall be
construed to limit the right of the Company, any Parent Corporation or any
Subsidiary Corporation to: (a) establish any other forms of incentives or
compensation for employees of the Company, any Parent Corporation or any
Subsidiary Corporation, or (b) grant or assume options otherwise than under the
Plan in connection with any proper corporate purpose, including, but not by way
of limitation, the grant or assumption of options in connection with the
acquisition, by purchase, lease, merger, consolidation or otherwise, of the
business, stock or assets of any corporation, firm or association.

      18. CONDITIONS TO ISSUANCE OF STOCK CERTIFICATES. The Company shall not be
required to issue or deliver any certificate or certificates for shares of Stock
purchased upon the exercise of Options prior to fulfillment of all the following
conditions:

            (a) The admission of such shares to listing on all stock exchanges,
if any, on which is then listed;

            (b) The completion of any registration or other qualification of
such shares under any state or federal law or under the rulings or regulations
of the Securities and Exchange Commission or any other governmental regulatory
body, which the Committee shall, in its absolute discretion, deem necessary or
advisable;

            (c) The obtaining of any approval or other clearance from any state
or federal governmental agency which the Committee shall, in its absolute
discretion, determine to be necessary or advisable;

            (d) The payment to the Company of all amounts which it is required
to withhold under federal, state or local law upon exercise of the Option; and

            (e) The lapse of such reasonable period of time following the
exercise of the Option as the Committee may from time to time establish for
reasons of administrative convenience.

      19. NOTIFICATION OF DISPOSITION. Each Employee shall give prompt notice to
the Company of any disposition or other transfer of any shares of Stock
purchased upon exercise of an Option if such disposition or transfer is made:
(a) within two (2) years from the Date of Grant of the Option, or (b) within one
(1) year after the transfer of such shares of Stock to such Employee upon
exercise of such Option. Such notice shall specify the date of such disposition
or other transfer and the amount realized, in cash, other property, assumption
of indebtedness or other consideration, by the Employee in such disposition or
other transfer.

      20. NOTICES. Any notice to be given under the terms of the Plan to the
Company shall be addressed to the Company in care of its Secretary and any
notice to be given to any Employee shall be addressed to such Employee at such
Employee's last address as reflected in the Company's records. By a notice given
pursuant to this Section, either party may designate a different address for
notices to be given to it, him or her. Any notice which is required to be given
to an Employee shall, if the Employee is then deceased, be given to the
Employee's personal representative if such representative has previously
informed the Company of his status and address by written notice under this
Section. Any notice shall have been deemed duly given if enclosed in a properly
sealed envelope or wrapper addressed as aforesaid at the time it is deposited
(with postage prepaid) in a post office or branch post office regularly
maintained by the United States Postal Service.

      21. HEADINGS. Headings are provided herein for convenience only and are
not to serve as a basis for interpretation or construction of the Plan. -

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<PAGE>
            I hereby certify that the Gen-Probe Incorporated Employee Stock
Purchase Plan was adopted by the Board of Directors of Gen-Probe Incorporated on
March 3, 2003 and by the Compensation Committee of the Board of Directors on
April 2, 2003.

            Executed on this 2nd day of April, 2003.

                                     /s/ R. William Bowen
                                     -------------------------------------
                                     R. William Bowen
                                     Secretary

                                  * * * * * * *

            I hereby certify that the Gen-Probe Incorporated Employee Stock
Purchase Plan was approved by the stockholders of Gen-Probe Incorporated on May
29, 2003.

            Executed on this 29th day of May, 2003.

                                     /s/ R. William Bowen
                                     -------------------------------------
                                     R. William Bowen
                                     Secretary

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