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                                                                     EXHIBIT 4.5



                                  ZYMETX, INC.
                          EMPLOYEE STOCK PURCHASE PLAN

         The ZymeTx, Inc. Employee Stock Purchase Plan (the "Plan") is intended
to provide the eligible employees of ZymeTx, Inc. (the"Company") and its
qualifying subsidiaries a convenient means of purchasing shares of the Company's
common stock, par value $.01 per share (the "Stock"). The Plan is intended to
qualify as an "employee stock purchase plan" under Section 423 of the Internal
Revenue Code of 1986, as amended (the "Code"), and shall be administered,
interpreted and construed in a manner consistent with the requirements of that
section of the Code.

                                    ARTICLE I
                                   DEFINITIONS

         1.1. "Account" means the book keeping account established on behalf of
each participant by the Administrator to record payroll deduction contributions
made by such Participant and shares of Stock purchased on his behalf.

         1.2. "Administrator" means the individual or committee appointed
pursuant to Article VIII to administer the Plan.

         1.3. "Board" means the Board of Directors of the Company.

         1.4. "Business Day" means each day on which the Exchange (as defined in
Section 4.2) is open for business.

         1.5. "Compensation" means all regular salary, wages or earnings but
excluding overtime, commissions, bonuses, amounts realized from the exercise of
a qualified or non-qualified stock option and other special incentive payments,
fees or allowances.

         1.6. "Effective Date" means July 1, 1998, subject to the provisions of
Section 9.8 of the Plan.

         1.7. "Employee" means any person who is employed by the Company except
an employee whose customary employment is:

              (a) less than 20 hours per week; or

              (b) less than 5 months a year.

For the purpose of determining whether an individual is an Employee, the
definition of Company shall also include the Company's subsidiaries, if any, as
defined under Code section 424(f).

         1.8. "Entry Date" means January 1, April 1, July 1, and October 1 of
each Plan Year.


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         1.9. "Offering Commencement Date" means the first Business Day of each
Offering Period.

         1.10. "Offering Period" means each three month period.

         1.11. "Offering Termination Date" means the last Business Day of each
Offering Period.

         1.12. "Participant" means an Employee who has met the eligibility
requirements of Article II and who has elected to participate pursuant to an
election under Section 3.1.

         1.13. "Plan Year" means the 12-month period ending December 31.

         1.14. "Shares" means shares of Stock that have been allocated to a
Participant's Account.

         1.15. "Three Months of Service" means a consecutive 3-month period
during which an individual was an Employee.

                                   ARTICLE II
                                   ELIGIBILITY

         2.1. Eligibility. Except as provided in Section 3.6, an Employee who
has completed Three Months of Service prior to the Effective Date and who
continues to be employed by the Company shall be eligible to participate in the
Plan as of the Effective Date. All other Employees, except as provided in
Section 3.6, shall be eligible to participate in the Plan as of the Entry Date
coinciding with or next following the completion of Three Months of Service.

         2.2. Eligibility Restrictions. A Participant who elects to terminate
participation in the Plan in accordance with Section 3.5 shall be prohibited
from participating in the Plan until the Entry Date next following the date of
such termination.

                                   ARTICLE III
                                  PARTICIPATION

         3.1. Commencement of Participation. An eligible Employee may become a
Participant in the Plan on any Entry Date by completing an enrollment and
payroll deduction form and delivering it to the Company in accordance with
procedures established by the Administrator.

         3.2. Payroll Deduction. At the time a Participant files his enrollment
and payroll deduction form, he shall elect to have after-tax deductions made
from his Compensation by a whole percentage that is not less than 1% nor more
than 10% of his Compensation.

         3.3. Participants' Accounts. All payroll deductions made from a
Participant's Compensation shall be credited to his Account and used to purchase
shares of Stock in accordance




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with Article V. Contributions credited to a Participant's Account shall not
accrue interest or earnings during the period prior to being used to purchase
shares of Stock in accordance with Article V.

         3.4. Changes in Payroll Deductions. The percentage designated by a
Participant as his rate of contribution under Section 3.2 shall automatically
apply to increases and decreases in his Compensation. Except as provided in
Section 3.5, a Participant may elect to change the rate of his contributions to
any other permissible rate effective as of the first day of the first payroll
period of any Offering Period provided the Participant files written notice with
the Administrator of an election to change his contribution rate at least ten
(10) Business Days before the effective date of the election.

         3.5. Suspension and Resumption of Payroll Deductions. A Participant may
terminate contributions under the Plan as of the first day of any payroll period
by filing written notice thereof with the Administrator at least ten (10)
Business Days before the effective date of the termination. A Participant who
has terminated his participation in the Plan in accordance with the preceding
provisions, shall be prohibited from resuming contributions under the Plan until
the following Entry Date. A Participant whose contributions have been terminated
in accordance with the preceding provisions, may resume contributions under the
Plan in accordance with Section 2.2.

         3.6. Restrictions on Participation. Notwithstanding any provisions of
the Plan to the contrary, no Employee shall be granted an option to participate
in the Plan under the following conditions:

              (a) No Employee shall be granted an option if, immediately after
         the grant, such Employee would own stock, and/or hold outstanding
         options to purchase stock, possessing 5% or more of the total combined
         voting power or value of all classes of stock of the Company (for
         purposes of this paragraph, the rules of Section 424(d) of the Code
         shall apply in determining stock ownership of any Employee); or

              (b) No Employee shall be granted an option which permits his
         rights to purchase Stock under the Plan and all other employee stock
         purchase plans (as described in Section 423 of the Code) of the Company
         to accrue at a rate which exceeds $25,000 of fair market value of such
         Stock (determined at the time such option is granted) for each calendar
         year in which such option is outstanding at any time. For purposes of
         this Section 3.6(b):

                  (i) the right to purchase Stock under an option accrues when
              the option (or any portion thereof) first becomes exercisable
              during the calendar year;

                  (ii) the right to purchase Stock under an option accrues at
              the rate provided in the option, but in no case may such rate
              exceed $25,000 of fair market value of such Stock (determined at
              the time such option is granted) for any one calendar year; and


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                  (iii) a right to purchase Stock which has accrued under one
              option granted pursuant to a plan may not be carried over to any
              other option.

                                   ARTICLE IV
                                    OFFERINGS

         4.1. Quarterly Offerings. The Plan shall be implemented through
quarterly offerings of the Company's Stock. Each Offering Period shall begin on
the Offering Commencement Date and shall end on the Offering Termination Date;
provided, however, if the first Offering Period commences prior to stockholder
approval of the Plan, the Offering Termination Date for such initial Offering
Period shall not occur until the end of the quarter in which stockholder
approval of the Plan is secured.

         4.2. Purchase Price. The "Purchase Price" per share of Stock with
respect to each Offering Period shall be the lesser of:

              (a) Eighty-five percent (85%) of the official closing price of the
         Stock on the Offering Termination Date on the Nasdaq National Market
         (or on such other national securities exchange upon which the Stock may
         then be listed, hereinafter referred to as the "Exchange") or if no
         sale of Stock occurred on such date, the official closing price on the
         preceding Business Day; or

              (b) Eighty-five percent (85%) of the official closing price of the
         Stock on the Offering Commencement Date on the Exchange (or if no sale
         of Stock occurred on such date, the closing price on the preceding
         business day).

         4.3. Maximum Offering. The maximum number of shares of Stock which
shall be issued under the Plan, subject to adjustment upon changes in
capitalization of the Company as provided in Section 9.3, shall be 50,000
shares. At the beginning of each Offering Period, the Board shall specify a
maximum number of shares which may be purchased by any Employee as well as a
maximum aggregate number of shares which may be purchased by all eligible
Employees pursuant to such quarterly offering. If the total number of shares
which would be purchased during any Offering Period exceeds the maximum number
of available shares, the Administrator shall make a pro rata allocation of the
available shares in a manner that it determines to be equitable and the balance
of payroll deductions credited to the Accounts of Participants shall be returned
to such Participants as soon as administratively practicable.

                                    ARTICLE V
                                PURCHASE OF STOCK

         5.1. Automatic Exercise. On each Offering Termination Date, each
Participant shall automatically and without any act on his part be deemed to
have purchased Stock to the full extent



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of the payroll deductions credited to his Account during the Offering Period
ending on such Offering Termination Date.

         5.2. Fractional Shares. Fractional shares of Stock may not be purchased
under the Plan.

         5.3. Acquisition of Stock. The Company may acquire Stock for use under
the Plan from authorized but unissued shares, treasury shares, in the open
market or in privately negotiated transactions.

         5.4. Accounting for Purchased Stock. All shares of Stock purchased
pursuant to Section 5.1 shall be allocated as Shares to the appropriate
Participant's Account as of the Offering Termination Date on which such shares
are purchased.

                                   ARTICLE VI
                                   ACCOUNTING

         6.1. General. The Administrator shall establish procedures to account
for payroll deductions made by a Participant, the number of Shares of Stock
purchased on a Participant's behalf and the number of Shares allocated to a
Participant's Account.

         6.2. Registration of Stock. Shares of Stock allocated to a
Participant's Account shall be registered in the name of the Company or its
nominee for the benefit of the Participant on whose behalf such shares were
purchased.

         6.3. Accounting for Distributions. Shares of Stock distributed or sold
from a Participant's Account shall be debited from his Account on a first-in,
first-out basis.

         6.4. Account Statements. Each Participant shall receive at least
semi-annual statements of all payroll deductions and shares of Stock allocated
to his Account together with all other transactions affecting his Account.

                                   ARTICLE VII
                          WITHDRAWALS AND DISTRIBUTIONS

         7.1. Withdrawal of Shares. A Participant may elect to withdraw any
number of Shares allocated to his Account by providing notification to the
Company in accordance with procedures established by the Administrator. As soon
as administratively practicable following notification of a Participant's
election to withdraw Shares, the Administrator shall cause a certificate
representing the number of Shares to be withdrawn to be delivered to the
Participant.

        7.2. Distribution Upon Termination. As soon as administratively
practicable after a Participant's termination of employment with the Company or
a participating subsidiary for any


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reason, a certificate representing all of such Participant's Shares shall be
distributed to him (or his executor, in the event of his death).

         7.3. Distribution of Payroll Deductions. In the event a Participant
terminates his employment with the Company or a participating subsidiary or his
participation in the Plan is terminated pursuant to Section 3.5, any payroll
deductions allocated to his Account and not yet applied to purchase Stock in
accordance with Section 5.1 shall be distributed to him in a cash lump sum as
soon as administratively practicable thereafter.


                                  ARTICLE VIII
                                 ADMINISTRATION

         8.1. Appointment of Administrator. The Board shall appoint an
individual or committee comprised of so many members as the Board shall
determine to administer the Plan. The Board may from time to time, if the Plan
is administered by a committee, appoint members to the committee in substitution
for or in addition to members previously appointed and may fill vacancies,
however caused, in the committee.

         8.2. Authority of Administrator. The Administrator shall have the
exclusive power and authority to administer the Plan, including, without
limitation, the right and power to interpret the provisions of the Plan and make
all determinations deemed necessary or advisable for the administration of the
Plan. All such actions, interpretations and determinations which are done or
made by the Administrator in good faith shall be final, conclusive and binding
on the Company, the Participants and all other parties and shall not subject the
Administrator to any liability.

         8.3. Administrator Procedures. The Administrator shall hold its
meetings at such times and places as it shall deem advisable and may hold
telephone meetings. In the event that the Administrator is a committee, a
majority of its members shall constitute a quorum and all determinations shall
be made by a majority of its members. Any decision or determination reduced to
writing and signed by the Administrator shall be as fully effective as if it had
been made by a majority vote at a meeting duly called and held. The
Administrator may appoint a secretary and shall make such rules and regulations
for the conduct of its business as it shall deem advisable.

         8.4. Expenses. The Company will pay all expenses incident to the
operation of the Plan, including the costs of record keeping, accounting fees,
legal fees and the costs of delivery of stock certificates to Participants.

                                   ARTICLE IX
                                  MISCELLANEOUS

         9.1. Transferability. Neither payroll deductions credited to a
Participant's Account nor any rights with regard to the purchase of Stock under
the Plan may be assigned, transferred, pledged


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or otherwise disposed of in any way by the Participant other than by will or the
laws of descent and distribution.

         9.2. Status as Owner. Each Participant shall be deemed to legally own
all shares of Stock allocated to his Account and shall be entitled to exercise
all rights associated with ownership of the shares, including, without
limitation, the right to vote such shares in all matters for which Stock is
entitled to vote, receive dividends, if any, and tender such shares in response
to a tender offer.

         9.3. Adjustment Upon Changes in Capitalization. In the event of a
reorganization, recapitalization, stock split, spin-off, split-off, split-up,
stock dividend, combination of shares, merger, consolidation or any other change
in the corporate structure of the Company, or a sale by the Company of all or
part of its assets, the Board may make appropriate adjustments in the number and
kind of shares which are subject to purchase under the Plan and in the exercise
price applicable to outstanding options.

         9.4. Amendment and Termination. The Board shall have complete power and
authority to terminate or amend the Plan (including without limitation the power
and authority to make any amendment that may be deemed to affect the interests
of any Participant adversely); provided, however, that the Board shall not,
without the approval of the shareholders of the Company (i) increase the maximum
number of shares which may be offered under the Plan (except pursuant to Section
9.3); (ii) modify the requirements as to eligibility for participation in the
Plan; or (iii) in any other way cause the Plan to fail the requirements of
Section 423 of the Code.

         The Plan and all rights of Employees hereunder shall terminate: (i) at
any time, at the discretion of the Board, in which case any cash balance in
Participants' Accounts shall be refunded to such Participants as soon as
administratively possible; or (ii) on the Offering Termination Date on which
Participants become entitled to purchase a number of shares of Stock that
exceeds the maximum number of shares available under the Plan.

         9.5. No Employment Rights. The Plan does not, directly or indirectly,
create in any Employee any right with respect to continuation of employment by
the Company and it shall not be deemed to interfere in any way with the
Company's right to terminate, or otherwise modify, an Employee's terms of
employment at any time.

         9.6. Withholding. To the extent any payments or distributions under
this Plan are subject to Federal, state or local taxes, the Company is
authorized to withhold all applicable taxes. The Company may satisfy its
withholding obligation by (i) withholding shares of Stock allocated to a
Participant's Account, (ii) deducting cash from a Participant's Account, or
(iii) deducting cash from a Participant's other compensation. A Participant's
election to participate in the Plan authorizes the Company to take any of the
actions described in the preceding sentence.



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         9.7. Use of Funds. All payroll deductions held by the Company under
this Plan may be used by the Company for any corporate purpose and the Company
shall not be obligated to hold such payroll deductions in trust or otherwise
segregate such amounts.

         9.8. Shareholder Approval. Notwithstanding the provision of Section 1.6
of the Plan, the Plan shall not take effect until approved by the shareholders
of the Company.

         9.9. Choice of Law. Except to the extent superseded by Federal law, the
laws of the State of Delaware will govern all matters relating to the Plan.

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         To record the adoption of the Plan, ZymeTx, Inc. has caused its
authorized officers to affix its Corporate name and seal this 18th day of
August, 1998.

                             ZYMETX, INC.



(SEAL)                       By: /s/ Peter G. Livingston,
                                -----------------------------------------------
   
                                     Peter G. Livingston, President and Chief
                             Executive Officer
 
ATTEST:


/s/ G. Carl Gibson
----------------------------
G. Carl Gibson, Secretary






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