
<PAGE>

                                                                    EXHIBIT 10.4

                                  AEROGEN, INC.

                           2000 EQUITY INCENTIVE PLAN


                            ADOPTED AUGUST 24, 2000
                 APPROVED BY STOCKHOLDERS _______________, 2000
                     TERMINATION DATE: _______________, 2010


1.       PURPOSES.

         (a)      ELIGIBLE STOCK AWARD RECIPIENTS. The persons eligible to
receive Stock Awards are the Employees, Directors and Consultants of the Company
and its Affiliates.

         (b)      AVAILABLE STOCK AWARDS. The purpose of the Plan is to provide
a means by which eligible recipients of Stock Awards may be given an opportunity
to benefit from increases in value of the Common Stock through the granting of
the following Stock Awards: (i) Incentive Stock Options, (ii) Nonstatutory Stock
Options, (iii) stock bonuses and (iv) rights to acquire restricted stock.

         (c)      GENERAL PURPOSE. The Company, by means of the Plan, seeks to
retain the services of the group of persons eligible to receive Stock Awards, to
secure and retain the services of new members of this group and to provide
incentives for such persons to exert maximum efforts for the success of the
Company and its Affiliates.

2.       DEFINITIONS.

         (a)      "AFFILIATE" means any parent corporation or subsidiary
corporation of the Company, whether now or hereafter existing, as those terms
are defined in Sections 424(e) and (f), respectively, of the Code.

         (b)      "BOARD" means the Board of Directors of the Company.

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

         (d)      "COMMITTEE" means a committee of one or more members of the
Board appointed by the Board in accordance with subsection 3(c).

         (e)      "COMMON STOCK" means the common stock of the Company.

         (f)      "COMPANY" means AeroGen, Inc., a Delaware corporation.

         (g)      "CONSULTANT" means any person, including an advisor, (i)
engaged by the Company or an Affiliate to render consulting or advisory services
and who is compensated for such services or (ii) who is a member of the Board of
Directors of an Affiliate. However, the


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term "Consultant" shall not include either Directors who are not compensated by
the Company for their services as Directors or Directors who are merely paid a
director's fee by the Company for their services as Directors.

         (h)      "CONTINUOUS SERVICE" means that the Participant's service with
the Company or an Affiliate, whether as an Employee, Director or Consultant, is
not interrupted or terminated. The Participant's Continuous Service shall not be
deemed to have terminated merely because of a change in the capacity in which
the Participant renders service to the Company or an Affiliate as an Employee,
Consultant or Director or a change in the entity for which the Participant
renders such service, provided that there is no interruption or termination of
the Participant's Continuous Service. For example, a change in status from an
Employee of the Company to a Consultant of an Affiliate or a Director will not
constitute an interruption of Continuous Service. The Board or the chief
executive officer of the Company, in that party's sole discretion, may determine
whether Continuous Service shall be considered interrupted in the case of any
leave of absence approved by that party, including sick leave, military leave or
any other personal leave.

         (i)      "COVERED EMPLOYEE" means the chief executive officer and the
four (4) other highest compensated officers of the Company for whom total
compensation is required to be reported to stockholders under the Exchange Act,
as determined for purposes of Section 162(m) of the Code.

         (j)      "DIRECTOR" means a member of the Board of Directors of the
Company.

         (k)      "DISABILITY" means the permanent and total disability of a
person within the meaning of Section 22(e)(3) of the Code.

         (l)      "EMPLOYEE" means any person employed by the Company or an
Affiliate. Mere service as a Director or payment of a director's fee by the
Company or an Affiliate shall not be sufficient to constitute "employment" by
the Company or an Affiliate.

         (m)      "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

         (n)      "FAIR MARKET VALUE" means, as of any date, the value of the
Common Stock determined as follows:

                  (i)      If the Common Stock is listed on any established
stock exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap
Market, the Fair Market Value of a share of Common Stock shall be the closing
sales price for such stock (or the closing bid, if no sales were reported) as
quoted on such exchange or market (or the exchange or market with the greatest
volume of trading in the Common Stock) on the last market trading day prior to
the day of determination, as reported in THE WALL STREET JOURNAL or such other
source as the Board deems reliable.

                  (ii)     In the absence of such markets for the Common Stock,
the Fair Market Value shall be determined in good faith by the Board.


                                       2.
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         (o)      "INCENTIVE STOCK OPTION" means an Option intended to qualify
as an incentive stock option within the meaning of Section 422 of the Code and
the regulations promulgated thereunder.

         (p)      "NON-EMPLOYEE DIRECTOR" means a Director who either (i) is not
a current Employee or Officer of the Company or its parent or a subsidiary, does
not receive compensation (directly or indirectly) from the Company or its parent
or a subsidiary for services rendered as a consultant or in any capacity other
than as a Director (except for an amount as to which disclosure would not be
required under Item 404(a) of Regulation S-K promulgated pursuant to the
Securities Act ("Regulation S-K")), does not possess an interest in any other
transaction as to which disclosure would be required under Item 404(a) of
Regulation S-K and is not engaged in a business relationship as to which
disclosure would be required under Item 404(b) of Regulation S-K; or (ii) is
otherwise considered a "non-employee director" for purposes of Rule 16b-3.

         (q)      "NONSTATUTORY STOCK OPTION" means an Option not intended to
qualify as an Incentive Stock Option.

         (r)      "OFFICER" means a person who is an officer of the Company
within the meaning of Section 16 of the Exchange Act and the rules and
regulations promulgated thereunder.

         (s)      "OPTION" means an Incentive Stock Option or a Nonstatutory
Stock Option granted pursuant to the Plan.

         (t)      "OPTION AGREEMENT" means a written agreement between the
Company and an Optionholder evidencing the terms and conditions of an individual
Option grant. Each Option Agreement shall be subject to the terms and conditions
of the Plan.

         (u)      "OPTIONHOLDER" means a person to whom an Option is granted
pursuant to the Plan or, if applicable, such other person who holds an
outstanding Option.

         (v)      "OUTSIDE DIRECTOR" means a Director who either (i) is not a
current employee of the Company or an "affiliated corporation" (within the
meaning of Treasury Regulations promulgated under Section 162(m) of the Code),
is not a former employee of the Company or an "affiliated corporation" receiving
compensation for prior services (other than benefits under a tax qualified
pension plan), was not an officer of the Company or an "affiliated corporation"
at any time and is not currently receiving direct or indirect remuneration from
the Company or an "affiliated corporation" for services in any capacity other
than as a Director or (ii) is otherwise considered an "outside director" for
purposes of Section 162(m) of the Code.

         (w)      "PARTICIPANT" means a person to whom a Stock Award is granted
pursuant to the Plan or, if applicable, such other person who holds an
outstanding Stock Award.

         (x)      "PLAN" means this AeroGen, Inc. 2000 Equity Incentive Plan.

         (y)      "RULE 16B-3" means Rule 16b-3 promulgated under the Exchange
Act or any successor to Rule 16b-3, as in effect from time to time.

         (z)      "SECURITIES ACT" means the Securities Act of 1933, as amended.


                                       3.
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         (aa)     "STOCK AWARD" means any right granted under the Plan,
including an Option, a stock bonus and a right to acquire restricted stock.

         (bb)     "STOCK AWARD AGREEMENT" means a written agreement between the
Company and a holder of a Stock Award evidencing the terms and conditions of an
individual Stock Award grant. Each Stock Award Agreement shall be subject to the
terms and conditions of the Plan.

         (cc)     "TEN PERCENT STOCKHOLDER" means a person who owns (or is
deemed to own pursuant to Section 424(d) of the Code) stock possessing more than
ten percent (10%) of the total combined voting power of all classes of stock of
the Company or of any of its Affiliates.

3.       ADMINISTRATION.

         (a)      ADMINISTRATION BY BOARD. The Board shall administer the Plan
unless and until the Board delegates administration to a Committee, as provided
in subsection 3(c).

         (b)      POWERS OF BOARD. The Board shall have the power, subject to,
and within the limitations of, the express provisions of the Plan:

                  (i)      To determine from time to time which of the persons
eligible under the Plan shall be granted Stock Awards; when and how each Stock
Award shall be granted; what type or combination of types of Stock Award shall
be granted; the provisions of each Stock Award granted (which need not be
identical), including the time or times when a person shall be permitted to
receive Common Stock pursuant to a Stock Award; and the number of shares of
Common Stock with respect to which a Stock Award shall be granted to each such
person.

                  (ii)     To construe and interpret the Plan and Stock Awards
granted under it, and to establish, amend and revoke rules and regulations for
its administration. The Board, in the exercise of this power, may correct any
defect, omission or inconsistency in the Plan or in any Stock Award Agreement,
in a manner and to the extent it shall deem necessary or expedient to make the
Plan fully effective.

                  (iii)    To amend the Plan or a Stock Award as provided in
Section 12.

                  (iv)     Generally, to exercise such powers and to perform
such acts as the Board deems necessary or expedient to promote the best
interests of the Company which are not in conflict with the provisions of the
Plan.

         (c)      DELEGATION TO COMMITTEE.

                  (i)      GENERAL. The Board may delegate administration of the
Plan to a Committee or Committees of one (1) or more members of the Board, and
the term "Committee" shall apply to any person or persons to whom such authority
has been delegated. If administration is delegated to a Committee, the Committee
shall have, in connection with the administration of the Plan, the powers
theretofore possessed by the Board, including the power to delegate to a
subcommittee any of the administrative powers the Committee is authorized to
exercise (and references in this Plan to the Board shall thereafter be to the
Committee or subcommittee), subject, however, to such resolutions, not
inconsistent with the provisions of the


                                       4.
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Plan, as may be adopted from time to time by the Board. The Board may abolish
the Committee at any time and revest in the Board the administration of the
Plan.

                  (ii)     COMMITTEE COMPOSITION WHEN COMMON STOCK IS PUBLICLY
TRADED. At such time as the Common Stock is publicly traded, in the discretion
of the Board, a Committee may consist solely of two or more Outside Directors,
in accordance with Section 162(m) of the Code, and/or solely of two or more
Non-Employee Directors, in accordance with Rule 16b-3. Within the scope of such
authority, the Board or the Committee may (1) delegate to a committee of one or
more members of the Board who are not Outside Directors the authority to grant
Stock Awards to eligible persons who are either (a) not then Covered Employees
and are not expected to be Covered Employees at the time of recognition of
income resulting from such Stock Award or (b) not persons with respect to whom
the Company wishes to comply with Section 162(m) of the Code and/or (2)
delegate to a committee of one or more members of the Board who are not
Non-Employee Directors the authority to grant Stock Awards to eligible persons
who are not then subject to Section 16 of the Exchange Act.

         (d)      EFFECT OF BOARD'S DECISION. All determinations,
interpretations and constructions made by the Board in good faith shall not be
subject to review by any person and shall be final, binding and conclusive on
all persons.

4.       SHARES SUBJECT TO THE PLAN.

         (a)      SHARE RESERVE. Subject to the provisions of Section 11
relating to adjustments upon changes in Common Stock, the Common Stock that may
be issued pursuant to Stock Awards shall not exceed in the aggregate three
million (3,000,000) shares of Common Stock.

         (b)      EVERGREEN SHARE RESERVE INCREASE.

                  (i)      Notwithstanding subsection 4(a) hereof, on the day
of each annual meeting of stockholders of the Company (the "Calculation
Date") for a period of ten (10) years, commencing with the annual meeting of
stockholders in 2001, the aggregate number of shares of Common Stock that is
available for issuance under the Plan shall automatically be increased by
that number of shares equal to the least of (1) four and one-half percent
(4.5%) of the Diluted Shares Outstanding; (2) six million (6,000,000) number
of shares of Common Stock; or (3) such lesser number of shares as determined
by the Board.

                  (ii)     "Diluted Shares Outstanding" shall mean, as of any
date, (1) the number of outstanding shares of Common Stock of the Company on
such Calculation Date, plus (2) the number of shares of Common Stock issuable
upon such Calculation Date assuming the conversion of all outstanding Preferred
Stock and convertible notes, plus (3) the additional number of dilutive Common
Stock equivalent shares outstanding as the result of any options or warrants
outstanding during the fiscal year, calculated using the treasury stock method.

         (c)      REVERSION OF SHARES TO THE SHARE RESERVE. If any Stock Award
shall for any reason expire or otherwise terminate, in whole or in part, without
having been exercised in full, the shares of Common Stock not acquired under
such Stock Award shall revert to and again become available for issuance under
the Plan. If any shares are repurchased, such repurchased


                                       5.
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shares shall revert back to and again become available for issuance under the
Plan for all Stock Awards other than Incentive Stock Options.

         (d)      SOURCE OF SHARES. The shares of Common Stock subject to the
Plan may be unissued shares or reacquired shares, bought on the market or
otherwise.

5.       ELIGIBILITY.

         (a)      ELIGIBILITY FOR SPECIFIC STOCK AWARDS. Incentive Stock Options
may be granted only to Employees. Stock Awards other than Incentive Stock
Options may be granted to Employees, Directors and Consultants.

         (b)      TEN PERCENT STOCKHOLDERS. A Ten Percent Stockholder shall not
be granted an Incentive Stock Option unless the exercise price of such Option is
at least one hundred ten percent (110%) of the Fair Market Value of the Common
Stock at the date of grant and the Option is not exercisable after the
expiration of five (5) years from the date of grant.

         (c)      SECTION 162(M) LIMITATION. Subject to the provisions of
Section 11 relating to adjustments upon changes in the shares of Common
Stock, no Employee shall be eligible to be granted Options covering more than
three million (3,000,000) shares of Common Stock during any calendar year.

         (d)      CONSULTANTS.

                  (i)      A Consultant shall not be eligible for the grant of a
Stock Award if, at the time of grant, a Form S-8 Registration Statement under
the Securities Act ("Form S-8") is not available to register either the offer or
the sale of the Company's securities to such Consultant because of the nature of
the services that the Consultant is providing to the Company, or because the
Consultant is not a natural person, or as otherwise provided by the rules
governing the use of Form S-8, unless the Company determines both (i) that such
grant (A) shall be registered in another manner under the Securities Act (E.G.,
on a Form S-3 Registration Statement) or (B) does not require registration under
the Securities Act in order to comply with the requirements of the Securities
Act, if applicable, and (ii) that such grant complies with the securities laws
of all other relevant jurisdictions.

                  (ii)     Form S-8 generally is available to consultants and
advisors only if (i) they are natural persons; (ii) they provide bona fide
services to the issuer, its parents, its majority-owned subsidiaries or
majority-owned subsidiaries of the issuer's parent; and (iii) the services are
not in connection with the offer or sale of securities in a capital-raising
transaction, and do not directly or indirectly promote or maintain a market for
the issuer's securities.

6.       OPTION PROVISIONS.

         Each Option shall be in such form and shall contain such terms and
conditions as the Board shall deem appropriate. All Options shall be separately
designated Incentive Stock Options or Nonstatutory Stock Options at the time of
grant, and, if certificates are issued, a separate certificate or certificates
will be issued for shares of Common Stock purchased on exercise of each type of
Option. The provisions of separate Options need not be identical, but


                                       6.
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each Option shall include (through incorporation of provisions hereof by
reference in the Option or otherwise) the substance of each of the following
provisions:

         (a)      TERM. Subject to the provisions of subsection 5(b) regarding
Ten Percent Stockholders, no Incentive Stock Option shall be exercisable after
the expiration of ten (10) years from the date it was granted.

         (b)      EXERCISE PRICE OF AN INCENTIVE STOCK OPTION. Subject to the
provisions of subsection 5(b) regarding Ten Percent Stockholders, the exercise
price of each Incentive Stock Option shall be not less than one hundred percent
(100%) of the Fair Market Value of the Common Stock subject to the Option on the
date the Option is granted. Notwithstanding the foregoing, an Incentive Stock
Option may be granted with an exercise price lower than that set forth in the
preceding sentence if such Option is granted pursuant to an assumption or
substitution for another option in a manner satisfying the provisions of Section
424(a) of the Code.

         (c)      EXERCISE PRICE OF A NONSTATUTORY STOCK OPTION. The exercise
price of each Nonstatutory Stock Option shall be not less than eighty-five
percent (85%) of the Fair Market Value of the Common Stock subject to the Option
on the date the Option is granted. Notwithstanding the foregoing, a Nonstatutory
Stock Option may be granted with an exercise price lower than that set forth in
the preceding sentence if such Option is granted pursuant to an assumption or
substitution for another option in a manner satisfying the provisions of Section
424(a) of the Code.

         (d)      CONSIDERATION. The purchase price of Common Stock acquired
pursuant to an Option shall be paid, to the extent permitted by applicable
statutes and regulations, either (i) in cash at the time the Option is exercised
or (ii) at the discretion of the Board at the time of the grant of the Option
(or subsequently in the case of a Nonstatutory Stock Option) (1) by delivery to
the Company of other Common Stock, (2) according to a deferred payment or other
similar arrangement with the Optionholder or (3) in any other form of legal
consideration that may be acceptable to the Board. Unless otherwise specifically
provided in the Option, the purchase price of Common Stock acquired pursuant to
an Option that is paid by delivery to the Company of other Common Stock
acquired, directly or indirectly from the Company, shall be paid only by shares
of the Common Stock of the Company that have been held for more than six (6)
months (or such longer or shorter period of time required to avoid a charge to
earnings for financial accounting purposes). At any time that the Company is
incorporated in Delaware, payment of the Common Stock's "par value," as defined
in the Delaware General Corporation Law, shall not be made by deferred payment.

         In the case of any deferred payment arrangement, interest shall be
compounded at least annually and shall be charged at the minimum rate of
interest necessary to avoid the treatment as interest, under any applicable
provisions of the Code, of any amounts other than amounts stated to be interest
under the deferred payment arrangement.

         (e)      TRANSFERABILITY OF AN INCENTIVE STOCK OPTION. An Incentive
Stock Option shall not be transferable except by will or by the laws of descent
and distribution and shall be exercisable during the lifetime of the
Optionholder only by the Optionholder. Notwithstanding


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the foregoing, the Optionholder may, by delivering written notice to the
Company, in a form satisfactory to the Company, designate a third party who, in
the event of the death of the Optionholder, shall thereafter be entitled to
exercise the Option.

         (f)      TRANSFERABILITY OF A NONSTATUTORY STOCK OPTION. A Nonstatutory
Stock Option shall be transferable to the extent provided in the Option
Agreement. If the Nonstatutory Stock Option does not provide for
transferability, then the Nonstatutory Stock Option shall not be transferable
except by will or by the laws of descent and distribution and shall be
exercisable during the lifetime of the Optionholder only by the Optionholder.
Notwithstanding the foregoing, the Optionholder may, by delivering written
notice to the Company, in a form satisfactory to the Company, designate a third
party who, in the event of the death of the Optionholder, shall thereafter be
entitled to exercise the Option.

         (g)      VESTING GENERALLY. The total number of shares of Common Stock
subject to an Option may, but need not, vest and therefore become exercisable in
periodic installments that may, but need not, be equal. The Option may be
subject to such other terms and conditions on the time or times when it may be
exercised (which may be based on performance or other criteria) as the Board may
deem appropriate. The vesting provisions of individual Options may vary. The
provisions of this subsection 6(g) are subject to any Option provisions
governing the minimum number of shares of Common Stock as to which an Option may
be exercised.

         (h)      TERMINATION OF CONTINUOUS SERVICE. In the event an
Optionholder's Continuous Service terminates (other than upon the Optionholder's
death or Disability), the Optionholder may exercise his or her Option (to the
extent that the Optionholder was entitled to exercise such Option as of the date
of termination) but only within such period of time ending on the earlier of (i)
the date three (3) months following the termination of the Optionholder's
Continuous Service (or such longer or shorter period specified in the Option
Agreement), or (ii) the expiration of the term of the Option as set forth in the
Option Agreement. If, after termination, the Optionholder does not exercise his
or her Option within the time specified in the Option Agreement, the Option
shall terminate.

         (i)      EXTENSION OF TERMINATION DATE. An Optionholder's Option
Agreement may also provide that if the exercise of the Option following the
termination of the Optionholder's Continuous Service (other than upon the
Optionholder's death or Disability) would be prohibited at any time solely
because the issuance of shares of Common Stock would violate the registration
requirements under the Securities Act, then the Option shall terminate on the
earlier of (i) the expiration of the term of the Option set forth in subsection
6(a) or (ii) the expiration of a period of three (3) months after the
termination of the Optionholder's Continuous Service during which the exercise
of the Option would not be in violation of such registration requirements.

         (j)      DISABILITY OF OPTIONHOLDER. In the event that an
Optionholder's Continuous Service terminates as a result of the Optionholder's
Disability, the Optionholder may exercise his or her Option (to the extent that
the Optionholder was entitled to exercise such Option as of the date of
termination), but only within such period of time ending on the earlier of (i)
the date twelve (12) months following such termination (or such longer or
shorter period specified in the Option Agreement) or (ii) the expiration of the
term of the Option as set forth in the Option


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Agreement. If, after termination, the Optionholder does not exercise his or her
Option within the time specified herein, the Option shall terminate.

         (k)      DEATH OF OPTIONHOLDER. In the event (i) an Optionholder's
Continuous Service terminates as a result of the Optionholder's death or (ii)
the Optionholder dies within the period (if any) specified in the Option
Agreement after the termination of the Optionholder's Continuous Service for a
reason other than death, then the Option may be exercised (to the extent the
Optionholder was entitled to exercise such Option as of the date of death) by
the Optionholder's estate, by a person who acquired the right to exercise the
Option by bequest or inheritance or by a person designated to exercise the
Option upon the Optionholder's death pursuant to subsection 6(e) or 6(f), but
only within the period ending on the earlier of (1) the date eighteen (18)
months following the date of death (or such longer or shorter period specified
in the Option Agreement) or (2) the expiration of the term of such Option as set
forth in the Option Agreement. If, after death, the Option is not exercised
within the time specified herein, the Option shall terminate.

         (l)      EARLY EXERCISE. The Option may, but need not, include a
provision whereby the Optionholder may elect at any time before the
Optionholder's Continuous Service terminates to exercise the Option as to any
part or all of the shares of Common Stock subject to the Option prior to the
full vesting of the Option. Any unvested shares of Common Stock so purchased may
be subject to a repurchase option in favor of the Company or to any other
restriction the Board determines to be appropriate.

7.       PROVISIONS OF STOCK AWARDS OTHER THAN OPTIONS.

         (a)      STOCK BONUS AWARDS. Each stock bonus agreement shall be in
such form and shall contain such terms and conditions as the Board shall deem
appropriate. The terms and conditions of stock bonus agreements may change from
time to time, and the terms and conditions of separate stock bonus agreements
need not be identical, but each stock bonus agreement shall include (through
incorporation of provisions hereof by reference in the agreement or otherwise)
the substance of each of the following provisions:

                  (i)      CONSIDERATION. A stock bonus may be awarded in
consideration for past services actually rendered to the Company or an Affiliate
for its benefit.

                  (ii)     VESTING. Shares of Common Stock awarded under the
stock bonus agreement may, but need not, be subject to a share reacquisition
option in favor of the Company in accordance with a vesting schedule to be
determined by the Board.

                  (iii)    TERMINATION OF PARTICIPANT'S CONTINUOUS SERVICE. In
the event a Participant's Continuous Service terminates, the Company may
reacquire any or all of the shares of Common Stock held by the Participant which
have not vested as of the date of termination under the terms of the stock bonus
agreement.

                  (iv)     TRANSFERABILITY. Rights to acquire shares of Common
Stock under the stock bonus agreement shall be transferable by the Participant
only upon such terms and conditions as are set forth in the stock bonus
agreement, as the Board shall determine in its


                                       9.
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discretion, so long as Common Stock awarded under the stock bonus agreement
remains subject to the terms of the stock bonus agreement.

         (b)      RESTRICTED STOCK PURCHASE AWARDS. Each restricted stock
purchase agreement shall be in such form and shall contain such terms and
conditions as the Board shall deem appropriate. The terms and conditions of the
restricted stock purchase agreements may change from time to time, and the terms
and conditions of separate restricted stock purchase agreements need not be
identical, but each restricted stock purchase agreement shall include (through
incorporation of provisions hereof by reference in the agreement or otherwise)
the substance of each of the following provisions:

                  (i)      PURCHASE PRICE. The purchase price under each
restricted stock purchase agreement shall be such amount as the Board shall
determine and designate in such restricted stock purchase agreement. The
purchase price shall not be less than eighty-five percent (85%) of the Common
Stock's Fair Market Value on the date such award is made or at the time the
purchase is consummated.

                  (ii)     CONSIDERATION. The purchase price of Common Stock
acquired pursuant to the restricted stock purchase agreement shall be paid
either: (i) in cash at the time of purchase; (ii) at the discretion of the
Board, according to a deferred payment or other similar arrangement with the
Participant; or (iii) in any other form of legal consideration that may be
acceptable to the Board in its discretion; provided, however, that at any time
that the Company is incorporated in Delaware, then payment of the Common Stock's
"par value," as defined in the Delaware General Corporation Law, shall not be
made by deferred payment.

                  (iii)    VESTING. Shares of Common Stock acquired under the
restricted stock purchase agreement may, but need not, be subject to a share
repurchase option in favor of the Company in accordance with a vesting schedule
to be determined by the Board.

                  (iv)     TERMINATION OF PARTICIPANT'S CONTINUOUS SERVICE. In
the event a Participant's Continuous Service terminates, the Company may
repurchase or otherwise reacquire any or all of the shares of Common Stock held
by the Participant which have not vested as of the date of termination under the
terms of the restricted stock purchase agreement.

                  (v)      TRANSFERABILITY. Rights to acquire shares of Common
Stock under the restricted stock purchase agreement shall be transferable by the
Participant only upon such terms and conditions as are set forth in the
restricted stock purchase agreement, as the Board shall determine in its
discretion, so long as Common Stock awarded under the restricted stock purchase
agreement remains subject to the terms of the restricted stock purchase
agreement.

8.       COVENANTS OF THE COMPANY.

         (a)      AVAILABILITY OF SHARES. During the terms of the Stock Awards,
the Company shall keep available at all times the number of shares of Common
Stock required to satisfy such Stock Awards.

         (b)      SECURITIES LAW COMPLIANCE. The Company shall seek to obtain
from each regulatory commission or agency having jurisdiction over the Plan such
authority as may be


                                      10.
<PAGE>

required to grant Stock Awards and to issue and sell shares of Common Stock upon
exercise of the Stock Awards; provided, however, that this undertaking shall not
require the Company to register under the Securities Act the Plan, any Stock
Award or any Common Stock issued or issuable pursuant to any such Stock Award.
If, after reasonable efforts, the Company is unable to obtain from any such
regulatory commission or agency the authority which counsel for the Company
deems necessary for the lawful issuance and sale of Common Stock under the Plan,
the Company shall be relieved from any liability for failure to issue and sell
Common Stock upon exercise of such Stock Awards unless and until such authority
is obtained.

9.       USE OF PROCEEDS FROM STOCK.

         Proceeds from the sale of Common Stock pursuant to Stock Awards shall
constitute general funds of the Company.

10.      MISCELLANEOUS.

         (a)      ACCELERATION OF EXERCISABILITY AND VESTING. The Board shall
have the power to accelerate the time at which a Stock Award may first be
exercised or the time during which a Stock Award or any part thereof will vest
in accordance with the Plan, notwithstanding the provisions in the Stock Award
stating the time at which it may first be exercised or the time during which it
will vest.

         (b)      STOCKHOLDER RIGHTS. No Participant shall be deemed to be the
holder of, or to have any of the rights of a holder with respect to, any shares
of Common Stock subject to such Stock Award unless and until such Participant
has satisfied all requirements for exercise of the Stock Award pursuant to its
terms.

         (c)      NO EMPLOYMENT OR OTHER SERVICE RIGHTS. Nothing in the Plan or
any instrument executed or Stock Award granted pursuant thereto shall confer
upon any Participant any right to continue to serve the Company or an Affiliate
in the capacity in effect at the time the Stock Award was granted or shall
affect the right of the Company or an Affiliate to terminate (i) the employment
of an Employee with or without notice and with or without cause, (ii) the
service of a Consultant pursuant to the terms of such Consultant's agreement
with the Company or an Affiliate or (iii) the service of a Director pursuant to
the Bylaws of the Company or an Affiliate, and any applicable provisions of the
corporate law of the state in which the Company or the Affiliate is
incorporated, as the case may be.

         (d)      INCENTIVE STOCK OPTION $100,000 LIMITATION. To the extent that
the aggregate Fair Market Value (determined at the time of grant) of Common
Stock with respect to which Incentive Stock Options are exercisable for the
first time by any Optionholder during any calendar year (under all plans of the
Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), the
Options or portions thereof which exceed such limit (according to the order in
which they were granted) shall be treated as Nonstatutory Stock Options.

         (e)      INVESTMENT ASSURANCES. The Company may require a Participant,
as a condition of exercising or acquiring Common Stock under any Stock Award,
(i) to give written assurances satisfactory to the Company as to the
Participant's knowledge and experience in financial and business matters and/or
to employ a purchaser representative reasonably satisfactory to the


                                      11.
<PAGE>

Company who is knowledgeable and experienced in financial and business matters
and that he or she is capable of evaluating, alone or together with the
purchaser representative, the merits and risks of exercising the Stock Award;
and (ii) to give written assurances satisfactory to the Company stating that the
Participant is acquiring Common Stock subject to the Stock Award for the
Participant's own account and not with any present intention of selling or
otherwise distributing the Common Stock. The foregoing requirements, and any
assurances given pursuant to such requirements, shall be inoperative if (1) the
issuance of the shares of Common Stock upon the exercise or acquisition of
Common Stock under the Stock Award has been registered under a then currently
effective registration statement under the Securities Act or (2) as to any
particular requirement, a determination is made by counsel for the Company that
such requirement need not be met in the circumstances under the then applicable
securities laws. The Company may, upon advice of counsel to the Company, place
legends on stock certificates issued under the Plan as such counsel deems
necessary or appropriate in order to comply with applicable securities laws,
including, but not limited to, legends restricting the transfer of the Common
Stock.

         (f)      WITHHOLDING OBLIGATIONS. To the extent provided by the terms
of a Stock Award Agreement, the Participant may satisfy any federal, state or
local tax withholding obligation relating to the exercise or acquisition of
Common Stock under a Stock Award by any of the following means (in addition to
the Company's right to withhold from any compensation paid to the Participant by
the Company) or by a combination of such means: (i) tendering a cash payment;
(ii) authorizing the Company to withhold shares of Common Stock from the shares
of Common Stock otherwise issuable to the Participant as a result of the
exercise or acquisition of Common Stock under the Stock Award, provided,
however, that no shares of Common Stock are withheld with a value exceeding the
minimum amount of tax required to be withheld by law; or (iii) delivering to the
Company owned and unencumbered shares of Common Stock.

11.      ADJUSTMENTS UPON CHANGES IN COMMON STOCK.

         (a)      CAPITALIZATION ADJUSTMENTS. If any change is made in the
Common Stock subject to the Plan, or subject to any Stock Award, without the
receipt of consideration by the Company (through merger, consolidation,
reorganization, recapitalization, reincorporation, stock dividend, dividend in
property other than cash, stock split, liquidating dividend, combination of
shares, exchange of shares, change in corporate structure or other transaction
not involving the receipt of consideration by the Company), the Plan will be
appropriately adjusted in the nature, class(es) and maximum number of securities
subject to the Plan pursuant to Section 4 and the maximum number of securities
subject to award to any person pursuant to subsection 5(c), and the outstanding
Stock Awards will be appropriately adjusted in the nature, class(es) and number
of securities and price per share of Common Stock subject to such outstanding
Stock Awards. The Board shall make such adjustments, and its determination shall
be final, binding and conclusive. (The conversion of any convertible securities
of the Company shall not be treated as a transaction "without receipt of
consideration" by the Company.)

         (b)      DISSOLUTION OR LIQUIDATION. In the event of a dissolution or
liquidation of the Company, then all outstanding Stock Awards shall terminate
immediately prior to such event.


                                      12.
<PAGE>

         (c)      ASSET SALE, MERGER, CONSOLIDATION OR REVERSE MERGER. In the
event of (i) a sale, lease or other disposition of all or substantially all of
the assets of the Company; (ii) a merger or consolidation in which the Company
is not the surviving corporation and in which beneficial ownership of securities
of the Company representing at least fifty percent (50%) of the combined voting
power entitled to vote in the election of the members of the Board of Directors
has changed; (iii) a reverse merger in which the Company is the surviving
corporation but the shares of the Company's Common Stock outstanding immediately
preceding the merger are converted by virtue of the merger into other property,
whether in the form of securities, cash or otherwise, and in which beneficial
ownership of securities of the Company representing at least fifty percent (50%)
of the combined voting power entitled to vote in the election of the member of
the Board of Directors has changed; (iv) an acquisition by any entity (other
than (A) a controlled affiliate of the Company, (B) any employee benefit plan,
or related trust, sponsored or maintained by the Company or subsidiary of the
Company or other entity controlled by the Company, or (C) any company owned
directly or indirectly by stockholders of the Company in substantially the same
proportions as their ownership of Common Stock interest of the Company,
immediately prior to the occurrence with respect to which the evaluation of the
Change in Control is being made) of the beneficial ownership, directly or
indirectly, of securities of the Company representing at least fifty percent
(50%) of the combined voting power of the Company's then outstanding securities;
or (v) in the event that the individuals who, as of the date of adoption of the
Plan, are members of the Company's Board of Directors (the "Incumbent Board"),
cease for any reason to constitute at least fifty percent (50%) of the Board of
Directors (if the election, or nomination for election by the Company's
stockholders, of any new Director is approved by a vote of at least fifty
percent (50%) of the Incumbent Board, such new Director shall be considered to
be a member of the Incumbent Board in the future), then any surviving
corporation or acquiring corporation shall assume any Stock Awards outstanding
under the Plan or shall substitute similar stock awards (including an award to
acquire the same consideration paid to the stockholders in the transaction
described in this subsection 11(c) for those outstanding under the Plan). In the
event any surviving corporation or acquiring corporation refuses to assume such
Stock Awards or to substitute similar stock awards for those outstanding under
the Plan, then with respect to Stock Awards held by Participants whose
Continuous Service has not terminated, the vesting of such Stock Awards (and, if
applicable, the time during which such Stock Awards may be exercised) shall be
accelerated in full, and the Stock Awards shall terminate if not exercised (if
applicable) at or prior to such event. With respect to any other Stock Awards
outstanding under the Plan, such Stock Awards shall terminate if not exercised
(if applicable) prior to such event.

12.      AMENDMENT OF THE PLAN AND STOCK AWARDS.

         (a)      AMENDMENT OF PLAN. The Board at any time, and from time to
time, may amend the Plan. However, except as provided in Section 11 relating to
adjustments upon changes in Common Stock, no amendment shall be effective unless
approved by the stockholders of the Company to the extent stockholder approval
is necessary to satisfy the requirements of Section 422 of the Code, Rule 16b-3
or any Nasdaq or securities exchange listing requirements.

         (b)      STOCKHOLDER APPROVAL. The Board may, in its sole discretion,
submit any other amendment to the Plan for stockholder approval, including, but
not limited to, amendments to the Plan intended to satisfy the requirements of
Section 162(m) of the Code and the regulations


                                      13.
<PAGE>

thereunder regarding the exclusion of performance-based compensation from the
limit on corporate deductibility of compensation paid to certain executive
officers.

         (c)      CONTEMPLATED AMENDMENTS. It is expressly contemplated that the
Board may amend the Plan in any respect the Board deems necessary or advisable
to provide eligible Employees with the maximum benefits provided or to be
provided under the provisions of the Code and the regulations promulgated
thereunder relating to Incentive Stock Options and/or to bring the Plan and/or
Incentive Stock Options granted under it into compliance therewith.

         (d)      NO IMPAIRMENT OF RIGHTS. Rights under any Stock Award granted
before amendment of the Plan shall not be impaired by any amendment of the Plan
unless (i) the Company requests the consent of the Participant and (ii) the
Participant consents in writing.

         (e)      AMENDMENT OF STOCK AWARDS. The Board at any time, and from
time to time, may amend the terms of any one or more Stock Awards; provided,
however, that the rights under any Stock Award shall not be impaired by any such
amendment unless (i) the Company requests the consent of the Participant and
(ii) the Participant consents in writing.

13.      TERMINATION OR SUSPENSION OF THE PLAN.

         (a)      PLAN TERM. The Board may suspend or terminate the Plan at
any time. Unless sooner terminated, the Plan shall terminate on the day
before the tenth (10th) anniversary of the date the Plan is adopted by the
Board or approved by the stockholders of the Company, whichever is earlier.
No Stock Awards may be granted under the Plan while the Plan is suspended or
after it is terminated.

         (b)      NO IMPAIRMENT OF RIGHTS. Suspension or termination of the
Plan shall not impair rights and obligations under any Stock Award granted
while the Plan is in effect except with the written consent of the
Participant.

14.      EFFECTIVE DATE OF PLAN.

         The Plan shall become effective upon the effective date of the initial
public offering of the Company's Common Stock, but no Stock Award shall be
exercised (or, in the case of a stock bonus, shall be granted) unless and until
the Plan has been approved by the stockholders of the Company, which approval
shall be within twelve (12) months before or after the date the Plan is adopted
by the Board.

15.      CHOICE OF LAW.

         The law of the State of California shall govern all questions
concerning the construction, validity and interpretation of this Plan, without
regard to such state's conflict of laws rules.


                                      14.
<PAGE>


                                  AEROGEN, INC.
                           2000 EQUITY INCENTIVE PLAN

                             STOCK OPTION AGREEMENT
              (INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION)


         Pursuant to your Stock Option Grant Notice ("Grant Notice") and this
Stock Option Agreement, AeroGen, Inc. (the "Company") has granted you an option
under its 2000 Equity Incentive Plan (the "Plan") to purchase the number of
shares of the Company's Common Stock indicated in your Grant Notice at the
exercise price indicated in your Grant Notice. Defined terms not explicitly
defined in this Stock Option Agreement but defined in the Plan shall have the
same definitions as in the Plan.

         The details of your option are as follows:

         1.       VESTING. Subject to the limitations contained herein, your
option will vest as provided in your Grant Notice, provided that vesting will
cease upon the termination of your Continuous Service.

         2.       NUMBER OF SHARES AND EXERCISE PRICE. The number of shares of
Common Stock subject to your option and your exercise price per share referenced
in your Grant Notice may be adjusted from time to time for Capitalization
Adjustments, as provided in the Plan.

         3.       EXERCISE PRIOR TO VESTING ("EARLY EXERCISE"). If permitted in
your Grant Notice (i.e., the "Exercise Schedule" indicates that "Early Exercise"
of your option is permitted) and subject to the provisions of your option, you
may elect at any time that is both (i) during the period of your Continuous
Service and (ii) during the term of your option, to exercise all or part of your
option, including the nonvested portion of your option; provided, however, that:

         a.       a partial exercise of your option shall be deemed to cover
first vested shares of Common Stock and then the earliest vesting installment of
unvested shares of Common Stock;

         b.       any shares of Common Stock so purchased from installments that
have not vested as of the date of exercise shall be subject to the purchase
option in favor of the Company as described in the Company's form of Early
Exercise Stock Purchase Agreement;

         c.       you shall enter into the Company's form of Early Exercise
Stock Purchase Agreement with a vesting schedule that will result in the same
vesting as if no early exercise had occurred; and

         d.       if your option is an incentive stock option, then, as provided
in the Plan, to the extent that the aggregate Fair Market Value (determined at
the time of grant) of the shares of Common Stock with respect to which your
option plus all other incentive stock options you hold are exercisable for the
first time by you during any calendar year (under all plans of the Company and
its Affiliates) exceeds one hundred thousand dollars ($100,000), your option(s)
or


                                      1.
<PAGE>

portions thereof that exceed such limit (according to the order in which they
were granted) shall be treated as nonstatutory stock options.

         4.       METHOD OF PAYMENT. Payment of the exercise price is due in
full upon exercise of all or any part of your option. You may elect to make
payment of the exercise price in cash or by check or in any other manner
PERMITTED BY YOUR GRANT NOTICE, which may include one or more of the following:

         a.       In the Company's sole discretion at the time your option is
exercised and provided that at the time of exercise the Common Stock is publicly
traded and quoted regularly in THE WALL STREET JOURNAL, pursuant to a program
developed under Regulation T as promulgated by the Federal Reserve Board that,
prior to the issuance of Common Stock, results in either the receipt of cash (or
check) by the Company or the receipt of irrevocable instructions to pay the
aggregate exercise price to the Company from the sales proceeds.

         b.       Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in THE WALL STREET JOURNAL, by delivery of
already-owned shares of Common Stock either that you have held for the period
required to avoid a charge to the Company's reported earnings (generally six
months) or that you did not acquire, directly or indirectly from the Company,
that are owned free and clear of any liens, claims, encumbrances or security
interests, and that are valued at Fair Market Value on the date of exercise.
"Delivery" for these purposes, in the sole discretion of the Company at the time
you exercise your option, shall include delivery to the Company of your
attestation of ownership of such shares of Common Stock in a form approved by
the Company. Notwithstanding the foregoing, you may not exercise your option by
tender to the Company of Common Stock to the extent such tender would violate
the provisions of any law, regulation or agreement restricting the redemption of
the Company's stock.

         c.       Pursuant to the following deferred payment alternative:

            1)          Not less than one hundred percent (100%) of the
aggregate exercise price, plus accrued interest, shall be due four (4) years
from date of exercise or, at the Company's election, upon termination of your
Continuous Service.

            2)          Interest shall be compounded at least annually and shall
be charged at the minimum rate of interest necessary to avoid the treatment as
interest, under any applicable provisions of the Code, of any portion of any
amounts other than amounts stated to be interest under the deferred payment
arrangement.

            3)          At any time that the Company is incorporated in
Delaware, payment of the Common Stock's "par value," as defined in the Delaware
General Corporation Law, shall be made in cash and not by deferred payment.

            4)          In order to elect the deferred payment alternative, you
must, as a part of your written notice of exercise, give notice of the election
of this payment alternative and, in order to secure the payment of the deferred
exercise price to the Company hereunder, if the Company so requests, you must
tender to the Company a promissory note and a security agreement covering the
purchased shares of Common Stock, both in form and substance


                                       2.
<PAGE>

satisfactory to the Company, or such other or additional documentation as the
Company may request.

         5.       WHOLE SHARES. You may exercise your option only for whole
shares of Common Stock.

         6.       SECURITIES LAW COMPLIANCE. Notwithstanding anything to the
contrary contained herein, you may not exercise your option unless the shares of
Common Stock issuable upon such exercise are then registered under the
Securities Act or, if such shares of Common Stock are not then so registered,
the Company has determined that such exercise and issuance would be exempt from
the registration requirements of the Securities Act. The exercise of your option
must also comply with other applicable laws and regulations governing your
option, and you may not exercise your option if the Company determines that such
exercise would not be in material compliance with such laws and regulations.

         7.       TERM. You may not exercise your option before the commencement
of its term or after its term expires. The term of your option commences on the
Date of Grant and expires upon the EARLIEST of the following:

         a.       three (3) months after the termination of your Continuous
Service for any reason other than your Disability or death, provided that if
during any part of such three (3) month period your option is not exercisable
solely because of the condition set forth in the preceding paragraph relating to
"Securities Law Compliance," your option shall not expire until the earlier of
the Expiration Date or until it shall have been exercisable for an aggregate
period of three (3) months after the termination of your Continuous Service;

         b.       twelve (12) months after the termination of your Continuous
Service due to your Disability;

         c.       eighteen (18) months after your death if you die either during
your Continuous Service or within three (3) months after your Continuous Service
terminates;

         d.       the Expiration Date indicated in your Grant Notice; or

         e.       the day before the tenth (10th) anniversary of the Date of
Grant.

         If your option is an incentive stock option, note that, to obtain the
federal income tax advantages associated with an "incentive stock option," the
Code requires that at all times beginning on the date of grant of your option
and ending on the day three (3) months before the date of your option's
exercise, you must be an employee of the Company or an Affiliate, except in the
event of your death or Disability. The Company has provided for extended
exercisability of your option under certain circumstances for your benefit but
cannot guarantee that your option will necessarily be treated as an "incentive
stock option" if you continue to provide services to the Company or an Affiliate
as a Consultant or Director after your employment terminates or if you otherwise
exercise your option more than three (3) months after the date your employment
terminates.


                                       3.
<PAGE>

         8.       EXERCISE.

         a.       You may exercise the vested portion of your option (and the
unvested portion of your option if your Grant Notice so permits) during its term
by delivering a Notice of Exercise (in a form designated by the Company)
together with the exercise price to the Secretary of the Company, or to such
other person as the Company may designate, during regular business hours,
together with such additional documents as the Company may then require.

         b.       By exercising your option you agree that, as a condition to
any exercise of your option, the Company may require you to enter into an
arrangement providing for the payment by you to the Company of any tax
withholding obligation of the Company arising by reason of (1) the exercise of
your option, (2) the lapse of any substantial risk of forfeiture to which the
shares of Common Stock are subject at the time of exercise, or (3) the
disposition of shares of Common Stock acquired upon such exercise.

         c.       If your option is an incentive stock option, by exercising
your option you agree that you will notify the Company in writing within fifteen
(15) days after the date of any disposition of any of the shares of the Common
Stock issued upon exercise of your option that occurs within two (2) years after
the date of your option grant or within one (1) year after such shares of Common
Stock are transferred upon exercise of your option.

         9.       TRANSFERABILITY. Your option is not transferable, except by
will or by the laws of descent and distribution, and is exercisable during your
life only by you. Notwithstanding the foregoing, by delivering written notice to
the Company, in a form satisfactory to the Company, you may designate a third
party who, in the event of your death, shall thereafter be entitled to exercise
your option.

         10.      RIGHT OF REPURCHASE. To the extent provided in the Company's
bylaws as amended from time to time, the Company shall have the right to
repurchase all or any part of the shares of Common Stock you acquire pursuant to
the exercise of your option.

         11.      OPTION NOT A SERVICE CONTRACT. Your option is not an
employment or service contract, and nothing in your option shall be deemed to
create in any way whatsoever any obligation on your part to continue in the
employ of the Company or an Affiliate, or of the Company or an Affiliate to
continue your employment. In addition, nothing in your option shall obligate the
Company or an Affiliate, their respective stockholders, Boards of Directors,
Officers or Employees to continue any relationship that you might have as a
Director or Consultant for the Company or an Affiliate.

         12.      WITHHOLDING OBLIGATIONS.

         a.       At the time you exercise your option, in whole or in part, or
at any time thereafter as requested by the Company, you hereby authorize
withholding from payroll and any other amounts payable to you, and otherwise
agree to make adequate provision for (including by means of a "cashless
exercise" pursuant to a program developed under Regulation T as promulgated by
the Federal Reserve Board to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company or an Affiliate, if any, which arise in connection
with your option.


                                       4.
<PAGE>

         b.       Upon your request and subject to approval by the Company, in
its sole discretion, and compliance with any applicable conditions or
restrictions of law, the Company may withhold from fully vested shares of Common
Stock otherwise issuable to you upon the exercise of your option a number of
whole shares of Common Stock having a Fair Market Value, determined by the
Company as of the date of exercise, not in excess of the minimum amount of tax
required to be withheld by law. If the date of determination of any tax
withholding obligation is deferred to a date later than the date of exercise of
your option, share withholding pursuant to the preceding sentence shall not be
permitted unless you make a proper and timely election under Section 83(b) of
the Code, covering the aggregate number of shares of Common Stock acquired upon
such exercise with respect to which such determination is otherwise deferred, to
accelerate the determination of such tax withholding obligation to the date of
exercise of your option. Notwithstanding the filing of such election, shares of
Common Stock shall be withheld solely from fully vested shares of Common Stock
determined as of the date of exercise of your option that are otherwise issuable
to you upon such exercise. Any adverse consequences to you arising in connection
with such share withholding procedure shall be your sole responsibility.

         c.       You may not exercise your option unless the tax withholding
obligations of the Company and/or any Affiliate are satisfied. Accordingly, you
may not be able to exercise your option when desired even though your option is
vested, and the Company shall have no obligation to issue a certificate for such
shares of Common Stock or release such shares of Common Stock from any escrow
provided for herein.

         13.      NOTICES. Any notices provided for in your option or the Plan
shall be given in writing and shall be deemed effectively given upon receipt or,
in the case of notices delivered by mail by the Company to you, five (5) days
after deposit in the United States mail, postage prepaid, addressed to you at
the last address you provided to the Company.

         14.      GOVERNING PLAN DOCUMENT. Your option is subject to all the
provisions of the Plan, the provisions of which are hereby made a part of your
option, and is further subject to all interpretations, amendments, rules and
regulations which may from time to time be promulgated and adopted pursuant to
the Plan. In the event of any conflict between the provisions of your option and
those of the Plan, the provisions of the Plan shall control.


                                       5.
<PAGE>

                                  AEROGEN, INC.
                            STOCK OPTION GRANT NOTICE
                          (2000 EQUITY INCENTIVE PLAN)


AeroGen, Inc. (the "Company"), pursuant to its 2000 Equity Incentive Plan (the
"Plan"), hereby grants to Optionholder an option to purchase the number of
shares of the Company's Common Stock set forth below. This option is subject to
all of the terms and conditions as set forth herein and in the Stock Option
Agreement, the Plan and the Notice of Exercise, all of which are attached hereto
and incorporated herein in their entirety.

<TABLE>

<S><C>
Optionholder:                         ________________________________________
Date of Grant:                        ________________________________________
Vesting Commencement Date:            ________________________________________
Number of Shares Subject to Option:   ________________________________________
Exercise Price (Per Share):           ________________________________________
Total Exercise Price:                 ________________________________________
Expiration Date:                      ________________________________________

TYPE OF GRANT:       / / Incentive Stock Option      / / Nonstatutory Stock Option

EXERCISE SCHEDULE:   / / Same as Vesting Schedule    / / Early Exercise Permitted

VESTING SCHEDULE:    1/4th  of the shares vest one year after the Vesting Commencement Date.
                     1/48th of the shares vest monthly thereafter over the next three years.

PAYMENT:             By one or a combination of the following items (described in the Stock Option Agreement):
</TABLE>

                               By cash or check
                               Pursuant to a Regulation T Program if the Shares
                               are publicly traded
                               By delivery of already-owned shares if the Shares
                               are publicly traded

ADDITIONAL TERMS/ACKNOWLEDGEMENTS: The undersigned Optionholder acknowledges
receipt of, and understands and agrees to, this Grant Notice, the Stock Option
Agreement and the Plan. Optionholder further acknowledges that as of the Date of
Grant, this Grant Notice, the Stock Option Agreement and the Plan set forth the
entire understanding between Optionholder and the Company regarding the
acquisition of stock in the Company and supersede all prior oral and written
agreements on that subject with the exception of (i) options previously granted
and delivered to Optionholder under the Plan, and (ii) the following agreements
only:

         OTHER AGREEMENTS:            _________________________________________
                                      _________________________________________

AEROGEN, INC.                                     OPTIONHOLDER:

By:_____________________________                  _____________________________
            Signature                                      Signature

Title                                             Date:
       -------------------------                       ------------------------
Date:
       -------------------------

ATTACHMENTS: Stock Option Agreement, 2000 Equity Incentive Plan and Notice of
Exercise


                                       1.
<PAGE>

                               NOTICE OF EXERCISE




AeroGen, Inc
1310 Orleans Drive
Sunnyvale, California  94089                  Date of Exercise: _______________

Ladies and Gentlemen:

         This constitutes notice under my stock option that I elect to purchase
the number of shares for the price set forth below.

<TABLE>

<S>                                                  <C>                        <C>
         Type of option (check one):                 Incentive  / /             Nonstatutory  / /

         Stock option dated:                         _______________

         Number of shares as
         to which option is
         exercised:                                  _______________

         Certificates to be
         issued in name of:                          _______________

         Total exercise price:                       $______________


         Cash payment delivered
         herewith:                                   $______________

         Value of ________ shares of
         AeroGen, Inc. common
         stock delivered herewith(1):                $______________

</TABLE>

--------------------------------
(1) Shares must meet the public trading requirements set forth in the option.
Shares must be valued in accordance with the terms of the option being
exercised, must have been owned for the minimum period required in the option,
and must be owned free and clear of any liens, claims, encumbrances or security
interests. Certificates must be endorsed or accompanied by an executed
assignment separate from certificate.

                                       2.
<PAGE>

         By this exercise, I agree (i) to provide such additional documents as
you may require pursuant to the terms of the 2000 Equity Incentive Plan, (ii) to
provide for the payment by me to you (in the manner designated by you) of your
withholding obligation, if any, relating to the exercise of this option, and
(iii) if this exercise relates to an incentive stock option, to notify you in
writing within fifteen (15) days after the date of any disposition of any of the
shares of Common Stock issued upon exercise of this option that occurs within
two (2) years after the date of grant of this option or within one (1) year
after such shares of Common Stock are issued upon exercise of this option.

                                       Very truly yours,



                                       -----------------------------------------




                                       2.




