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EXHIBIT 10.5



                             COMBIMATRIX CORPORATION
                             1995 STOCK OPTION PLAN

SECTION 1. PURPOSE OF THE PLAN.

         The CombiMatrix Corporation 1995 Stock Option Plan is intended to
promote the interests of CombiMatrix Corporation, a California corporation, by
providing incentives to certain Employees who are responsible for the
management, growth, or financial success of the Corporation or its Subsidiary
Corporations. The plan will encourage such Employees to acquire a proprietary
interest, or to increase their proprietary interest, in the Corporation and will
thereby induce such Employees to continue to perform services for, and to
enhance the welfare of, the Corporation or its Subsidiary Corporations.

SECTION 2. DEFINITIONS.

         (a) "Award Date" shall mean the date on which an Optionee is granted an
Option.

         (b) "Board" shall mean the Board of Directors of the Corporation, as
constituted from time to time.

         (c) "Code" shall mean the Internal Revenue Code of 1986, as amended.

         (d) "Committee" shall mean a duly appointed committee of the Board as
described in Section 3(a).

         (e) "Corporation" shall mean CombiMatrix Corporation, a California
corporation.

         (f) "Employee" shall mean (i) any individual who is an employee of the
Corporation or of a Subsidiary Corporation, (ii) a member of the Board of
Directors of the Corporation or of a Subsidiary Corporation, and (iii) an
independent contractor who performs services as an advisor or consultant for the
Corporation or for a Subsidiary Corporation. Service as an Employee shall be
considered employment for all purposes of the Plan except the second sentence of
Section 4(a).

         (g) "Exercise Price" shall mean the amount for which one Share may be
purchased upon exercise of an Option, as specified by the Committee in the
applicable Stock Option Agreement.

         (h) "Fair Market Value" shall mean the fair market value of a Share, as
determined by the Committee in good faith. Any determination as to fair market
value made pursuant to this Plan shall be determined without regard to any
restriction other than a restriction which, by its terms, will never lapse, and
shall be conclusive and binding on all persons.

         (i) "ISO" shall mean an incentive stock option described in Section
422(b) of the Code.


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         (j) "Nonstatutory Option" shall mean a stock option not described in
Section 422(b) of the Code.

         (k) "Option" shall mean an ISO or Nonstatutory Option granted under the
Plan and entitling the holder to purchase Shares.

         (l) "Optionee" shall mean an individual who holds an Option.

         (m) "Parent Corporation" means any corporation (other than the
Corporation) in an unbroken chain of corporations ending with the Corporation
if, at the Award Date, each of the corporations other than the Corporation owns
stock possessing 50 percent or more of the total combined voting power of all
classes of stock in one of the other corporations in such chain.

         (n) "Plan" shall mean this CombiMatrix Corporation, 1995 Stock Option
Plan.

         (o) "Share" shall mean one share of Stock, as adjusted in accordance
with Section 9 (if applicable).

         (p) "Stock" shall mean the common stock, no par value, of the
Corporation.

         (q) "Stock Option Agreement" shall mean the agreement between the
Corporation and an Optionee, which contains the terms, conditions and
restrictions pertaining to such Optionee's Option.

         (r) "Subsidiary Corporation" shall mean any corporation, if the
Corporation and/or any of its Subsidiary Corporations own stock possessing not
less than 50 percent of the total combined voting power of all classes of stock
of such corporation. A corporation that attains the status of a Subsidiary
Corporation on a date after the adoption of the Plan shall be considered a
Subsidiary Corporation as of such date.

SECTION 3. ADMINISTRATION.

         (a) COMMITTEE MEMBERSHIP. The Plan shall be administered by the
Committee. If no Committee has been appointed, the entire Board shall constitute
the Committee. No member of the Committee or of the Board, when acting in the
capacity of director or Committee member, may exercise discretionary functions
as to any matter relating solely to such director or Committee member's own
interests under the Plan. Subject to the foregoing limitation, any member of the
Committee may be removed by the Board at any time either with or without cause,
and any vacancy on the Committee may be filled by the Board at any time.

         (b) COMMITTEE PROCEDURES. The Board shall designate one of the members
of the Committee as chairperson. The Committee may hold meetings at such times
and places as it shall determine. A majority of the members of the Committee
shall constitute a quorum, and the acts of a majority of the Committee members
present at meetings at which a quorum exists, or acts reduced to or approved in
writing by all Committee members, shall be valid acts of the Committee. In
making any determination or in taking or not taking any action under the Plan,
the Committee may obtain and may rely upon the advice of experts, including
professional advisors or consultants to the Corporation. The Committee may
delegate ministerial, non-discretionary functions to any Employee.

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         (c) COMMITTEE RESPONSIBILITIES. Subject to the provisions of the Plan,
the Committee shall have full authority and discretion to take the following
actions:

                  (i) To interpret and apply the provisions of the Plan or of
any Option granted thereunder;

                  (ii) To adopt, amend or rescind rules, procedures and forms
relating to the Plan or to any Option granted thereunder;

                  (iii) To authorize any person to execute, on behalf of the
Corporation, any instrument required to carry out the purposes of the Plan or of
any Option granted thereunder;

                  (iv) To determine when Options are to be granted under the
Plan;

                  (v) To select the Optionees;

                  (vi) To determine the number of Shares to be made subject to
each Option;

                  (vii) To prescribe the terms and conditions of each Option,
including (without limitation) the Exercise Price, the date or dates on which an
Option becomes exercisable, the installments (if any) in which such Option shall
become exercisable, the events of termination or reversion of such Option and
whether such Option is to be classified as an ISO or a Nonstatutory Option;

                  (viii) To determine whether an outstanding Stock Option
Agreement should be modified, extended or assumed, subject to applicable legal
restrictions;

                  (ix) To prescribe the considerations for the grant of each
Option or other right under the Plan and to determine the sufficiency of such
consideration; and

                  (x) To take any other actions deemed necessary or advisable
for the administration of the Plan.

                  All decisions, interpretations and other actions of the
Committee performed pursuant to the Plan shall be final and binding on Optionees
and all persons deriving their rights from an Optionee. No member of the
Committee shall be liable for any action that such member has taken or has
failed to take in good faith with respect to the Plan or any Option.

SECTION 4. ELIGIBILITY.

         (a) GENERAL RULE. Only Employees shall be eligible for designation as
Optionees by the Committee. In addition, only individuals who are employed as
employees by the Corporation or by a Subsidiary Corporation shall be eligible
for the grant of ISOs. Mere status as an Employee shall not entitle any person
to receive Options.

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         (b) TEN-PERCENT STOCKHOLDERS. An employee of the Corporation or of any
Subsidiary Corporation who, on the Award Date, owns stock possessing more than
10 percent of the total combined voting power of all classes of stock of the
Corporation, any Subsidiary Corporation, or any Parent Corporation shall not be
eligible for an ISO unless (i), as of the Award Date, the Exercise Price is at
least 110 percent of the Fair Market Value of a Share and (ii) such ISO by its
terms is not exercisable after the expiration of five years from the Award Date.

         (c) ATTRIBUTION RULES. For purposes of SubSection (b) above, in
determining stock ownership, an employee shall be deemed to own the stock owned,
directly or indirectly, by or for that employee's brothers, sisters, spouse,
ancestors and lineal descendants. Any stock owned, directly or indirectly, by or
for a corporation, partnership, estate or trust shall be deemed to be owned
proportionately by or for its stockholders, partners or beneficiaries. Any stock
with respect to which such employee holds an option shall not be counted.

SECTION 5. STOCK SUBJECT TO PLAN.

         (a) BASIC LIMITATION. All Shares issued under the Plan shall be
authorized but unissued Shares or treasury Shares. The aggregate number of
Shares issued under the Plan upon exercise of Options shall not exceed ______
Shares, subject to adjustment pursuant to Section 9. The number of Shares that
are subject to Options outstanding at any time under the Plan shall not exceed
the number of Shares that then remain available for issuance under the Plan
unless (i) an amendment to increase the maximum number of Shares issuable under
the Plan is adopted by the Board prior to the initial grant of any such Option
and is thereafter submitted to the Corporation's stockholders for approval and
(ii) each Option so granted is not to become exercisable, in whole or in part,
at any time prior to obtaining such stockholder approval.

         (b) ADDITIONAL SHARES. In the event that any outstanding Option for any
reason expires or is canceled or otherwise terminated, the Shares allocable to
the unexercised portion of such Option shall again be available for subsequent
grants of Options.

SECTION 6. TERMS AND CONDITIONS OF OPTIONS.

         (a) STOCK OPTION AGREEMENT. Each Nonstatutory Option and each ISO shall
be evidenced by a Stock Option Agreement in a form acceptable to the Corporation
and signed by the Corporation and the Optionee. Such Option shall be subject to
all applicable terms and conditions of the Plan and shall be subject to any
other terms and conditions which are not inconsistent with the Plan and which
the Committee deems appropriate for inclusion in a Stock Option Agreement. The
provisions of the various Stock Option Agreements need not be identical.

         (b) NUMBER OF SHARES. Each Stock Option Agreement shall specify the
number of Shares that are subject to the Option and shall provide for the
adjustment of such number in accordance with Section 9. The Stock Option
Agreement shall also specify whether the Option is an ISO or a Nonstatutory
Option. A Stock Option Agreement for an ISO will also provide that to the extent
the Aggregate Fair Market Value (at the time the ISO was granted) of Stock with
respect to which the ISO is exercisable on the first time by an Employee during
any calendar year exceeds $100,000, the ISOs will be treated as Nonstatutory
Options.

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         (c) EXERCISE PRICE. Each Stock Option Agreement shall specify the
Exercise Price. The Exercise Price of an ISO shall not be less than 100 percent
of the Fair Market Value of a Share on the Award Date, and a higher percentage
may be required by Section 4(b). The exercise of Nonstatutory Option shall not
be less than 90% of the Fair Market Value of a Share on the Award Date. Subject
to the preceding three sentences, the Exercise Price under any Option shall be
determined by the Committee at its sole discretion. The Exercise Price shall be
payable in a form described in Section 8.

         (d) WITHHOLDING TAXES. As a condition to the exercise of an Option, the
Optionee shall make such arrangements as the Committee may require for the
satisfaction of any federal, state, local or foreign withholding tax obligations
that may arise in connection with such exercise. The Optionee shall also make
such arrangements as the Committee may require for the satisfaction of any
federal, state, local, or foreign withholding tax obligations that may arise in
connection with the disposition of Shares acquired by exercising an Option.

         (e) TERM. Each Stock Option Agreement shall specify the term of the
Option. The term shall not exceed 10 years from the Award Date, except as
otherwise provided in Section 4(b).

         (f) EXERCISABILITY. Each Stock Option Agreement shall specify the date
when all or any installment of the Option is to become exercisable and vest. No
Option shall become exercisable prior to six months after the Award Date.

         (g) NONTRANSFERABILITY. No Option shall be transferable by the Optionee
other than by will or by the laws of descent and distribution. An Option may be
exercised during the lifetime of the Optionee only by the Optionee or by the
Optionee's guardian or legal representative. No Option or interest therein may
be transferred, assigned, pledged or hypothecated by the Optionee during the
Optionee's lifetime, whether by operation of law or otherwise, or be made
subject to execution, attachment or similar process.

         (h) EFFECT OF TERMINATION OF EMPLOYMENT. The Committee shall establish
in respect of each Option granted to an Employee the effect of a termination of
employment on the rights and benefits thereunder and in so doing may make
distinctions based upon the cause of termination. The effect of such termination
of employment shall be set forth in the applicable Stock Option Agreement.

         (i) NO RIGHTS AS A STOCKHOLDER. An Optionee, or a transferee of an
Optionee, shall have no rights as a stockholder with respect to any Shares
covered by an Option until the date of the issuance of a stock certificate for
such Shares.

         (j) RESTRICTIONS ON TRANSFER OF SHARES. To the extent that an
applicable Stock Option Agreement so provides, any Shares issued upon exercise
of an Option shall be subject to such special forfeiture conditions, rights of
repurchase, rights of first refusal and other transfer restrictions as the
Committee may determine. Such restrictions shall apply in addition to any
restrictions that may apply to holders of Shares generally.

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SECTION 7. MODIFICATION, EXTENSION AND ASSUMPTION OF OPTIONS.

         Within the limitations of the Plan, the Committee from time to time may
authorize, either generally or in specific cases only, modification, extension
or assumption of an outstanding Option. Such modification, extension or
assumption may be effected by any legally valid means, including by cancellation
of an outstanding Option and the subsequent regranting of an Option, by
amendment, by substitution of an outstanding Option, or by waiver and may result
in, among other changes, a higher or lower Exercise Price, a greater or lesser
number of Shares that are subject to the Option, different vesting dates, or a
longer or shorter term; provided, however, that no modification, extension or
assumption of an Option shall, without the consent of the Optionee, impair the
Optionee's rights or increase the Optionee's obligations under the Option.

SECTION 8. PAYMENT FOR SHARES.

         (a) GENERAL RULE. The entire Exercise Price of Shares issued under the
Plan shall be payable in lawful money of the United States of America or by a
certified or bank cashier's check, except as provided in Subsections (b), (c),
(d), and (e) below.

         (b) SURRENDER OF STOCK. To the extent an applicable Stock Option
Agreement so provides, payment may be made in whole or in part with Shares which
have already been owned by the Optionee or a representative of the Optionee for
more than six months and which are surrendered to the Corporation in good form
for transfer. Such Shares shall be valued at their Fair Market Value as of the
date when the new Shares are purchased under the Plan.

         (c) EXERCISE/SALE. To the extent that an applicable Stock Option
Agreement so provides, payment may be made in whole or in part by the delivery
(on a form prescribed by the Corporation) of an irrevocable direction to a
securities broker approved by the Corporation to sell Shares and to deliver all
or part of the sales proceeds to the Corporation in payment of all or part of
the Exercise Price and any withholding taxes.

         (d) EXERCISE/PLEDGE. To the extent an applicable Stock Option Agreement
so provides, payment may be made in whole or in part by a promissory note
executed by the Optionee in favor of the Corporation, upon terms and conditions
determined by the Committee, and secured by the Stock issuable upon exercise of
such Option in compliance with applicable law (including, without limitation,
state corporate law and federal margin requirements).

         (e) OTHER METHODS OF PAYMENT. To the extent an applicable Stock Option
Agreement so provides, payment may be made in whole or in part by any other
means deemed acceptable by the Committee.

SECTION 9. ADJUSTMENT OF SHARES.

         (a) GENERAL. In the event of a subdivision of the outstanding Stock, a
declaration of a dividend payable in Shares, a declaration of an extraordinary
dividend payable in a form other than Shares in an amount that has a material
effect on the value of Shares, an issuance of Stock or other securities in an
amount that has a material effect on the value of Shares, a combination or
consolidation of the outstanding Stock into a lesser number of Shares, a


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recapitalization, a spinoff, a reclassification or a similar occurrence, the
Committee shall make appropriate adjustments in one or more of (i) the number of
Shares available for future grants under Section 5, (ii) the number of Shares
covered by each outstanding Option, (iii) the Exercise Price under each
outstanding Option or (iv) any other provision in the outstanding Stock Option
Agreements that the Committee deems necessary or advisable to adjust.

         (b) REORGANIZATIONS. In the event that the Corporation is a party to a
merger or other reorganization, or in contemplation of such a merger or other
reorganization, and to the extent that applicable Stock Option Agreements so
provide, the Committee may, in its sole discretion, take one or a combination of
the following actions:

                  (i) provide that Options may be terminated upon payment to
Optionees of the difference between the Exercise Price and the consideration to
be received by stockholders of the Corporation for "in-the-money" options and
that all other Options may be terminated without payment therefor of any kind,

                  (ii) provide for the assumption, by the surviving corporation
or its parent, of some or all of the outstanding Options;

                  (iii) if the Corporation is a surviving corporation, direct
the Corporation to continue some or all of the outstanding Options;

                  (iv) authorize the immediate and full vesting of some or all
of the outstanding Options, followed by cancellation if not exercised; or
(v)take any other action with respect to some or all of the Options that the
Committee deems necessary or advisable.

         (c) RESERVATION OF RIGHTS. Except as provided in this Section 9, an
Optionee shall have no rights by reason of (i) any subdivision or consolidation
of shares of stock of any class, (ii) the payment of any dividend or (iii) any
other increase or decrease in the number of shares of stock of any class. The
grant of an Option pursuant to the Plan shall not affect in any way the right or
power of the Corporation to make adjustments, reclassifications, reorganizations
or changes of its capital or business structure, to merge or consolidate or to
dissolve, liquidate, sell or transfer all or any part of its business or assets.

SECTION 10. SECURITIES LAWS.

         Shares shall not be issued under the Plan unless the issuance and
delivery of such Shares comply with (or are exempt from) all applicable
requirements of law, including (without limitation) the Securities Act of 1933,
as amended, the rules and regulations promulgated thereunder, state securities
laws and regulations, and the regulations of any stock exchange on which the
Corporation's securities may then be listed. Optionees may be required by the
Committee, as a condition to exercising any Option, to represent to the
Corporation in writing that the Shares are being acquired by them for investment
only and not with a view to the resale or distribution thereof.

SECTION 11. NO EMPLOYMENT RIGHTS.

         No provision of the Plan, nor any right or Option granted under the
Plan, shall be construed to give any person any right to become, to be treated
as, or to remain an Employee, or be interpreted so as to interfere with the
Corporation's or any Subsidiary Corporation's right to determine the Optionee's
other compensation, including salary.

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SECTION 12. DURATION AND AMENDMENTS.

         (a) TERM OF THE PLAN. The Plan, as set forth herein, shall become
effective on the date of its adoption by the Board, subject to the approval of
the Corporation's stockholders. In the event that the stockholders fail to
approve the Plan on or before the date 12 months after its adoption by the
Board, (i) the Plan shall terminate, (ii) any Options already granted shall be
canceled and (iii) any Shares already issued under the Plan shall be repurchased
by the Corporation at the original Exercise Price. The Plan shall terminate
automatically 10 years after its adoption by the Board and may be terminated on
any earlier date pursuant to SubSection (b) below.

         (b) RIGHT TO AMEND OR TERMINATE THE PLAN. The Board may amend, suspend
or terminate the Plan at any time and for any reason; provided, however, that
any amendment of the Plan which increases the number of Shares available for
issuance under the Plan (except as provided in Section 9), or which materially
changes the class of persons who are eligible for the grant of ISOs, shall be
subject to the approval of the Corporation's stockholders. Unless required by
applicable law, stockholder approval shall not be required for any other
amendment of the Plan.

         (c) EFFECT OF AMENDMENT OR TERMINATION. No Shares shall be issued or
sold under the Plan after the termination thereof, except upon exercise of an
Option granted prior to such termination. The termination of the Plan, or any
amendment thereof, shall not affect any Share previously issued or any Option
previously granted under the Plan (except as provided in SubSection (a) above).

SECTION 13. GOVERNING LAW.

         The interpretation, performance and enforcement of this Plan shall be
governed by the laws of the State of California.

SECTION 14. EXECUTION.

         To record the adoption of the Plan by the Board, the Corporation has
caused its authorized officer to execute the same.

                                         COMBIMATRIX CORPORATION

                                         By:
                                                --------------------------------
                                         Name:
                                                --------------------------------
                                         Title:
                                                --------------------------------





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                 FIRST AMENDMENT TO THE COMBIMATRIX CORPORATION
                             1995 STOCK OPTION PLAN

                              W I T N E S S E T H:

         WHEREAS, CombiMatrix Corporation (the "Company") presently maintains
the CombiMatrix Corporation 1995 Stock Option Plan which became effective on
____________, 1996 (the "Plan"); and

         WHEREAS, the Company, pursuant to Section 12 of the Plan, has the right
to amend the Plan from time to time subject to certain limitations; and

         WHEREAS, effective September 14, 2000 ("Effective Date"), the Company
changed from being a California corporation to become a Delaware corporation;
and

         WHEREAS, the Company desires to amend the Plan so that the Options (as
defined in the Plan) granted after the Effective Date are subject to the laws of
the state of Delaware.

         NOW, THEREFORE, in order to make certain revisions desired by the
Company, the Plan is hereby amended in the following manner:

         1. Effective as of the Effective Date, the first sentence of Section 1
of the Plan is hereby amended in its entirety to read as follows:

                  The CombiMatrix Corporation 1995 Stock Option Plan is intended
                  to promote the interest of CombiMatrix Corporation, a Delaware
                  corporation, by providing incentives to certain Employees who
                  are responsible for the management, growth, or financial
                  success of the Corporation or its Subsidiary Corporations.

         2. Effective as of the Effective Date, Section 2.(e) of the Plan is
hereby amended in its entirety to read as follows:

                  (e) "Corporation" shall mean CombiMatrix Corporation, a
                  Delaware corporation.

         3. Effective as of the Effective Date, Section 13 of the Plan is hereby
amended in its entirety to read as follows:

                  Section 13. GOVERNING LAW

                  The interpretation, performance and enforcement of this Plan
                  shall be governed by the laws of the State of Delaware.

         IN WITNESS WHEREOF, CombiMatrix Corporation has caused this First
Amendment to the CombiMatrix 1995 Stock Option Plan to be executed on this day
of __________, 2000.

                                         COMBIMATRIX CORPORATION

                                         By:
                                             -----------------------------------



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