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                                                                   EXHIBIT 10.16






                            ACLARA BIOSCIENCES, INC.

                          EMPLOYEE STOCK PURCHASE PLAN





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                            ACLARA BIOSCIENCES, INC.

                          EMPLOYEE STOCK PURCHASE PLAN


                                TABLE OF CONTENTS



<TABLE>
<CAPTION>
                                                                                           PAGE
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<S>     <C>                                                                                 <C>
1.      Definitions..........................................................................1
2.      Stock Subject to the Plan............................................................3
3.      Grant of Options.....................................................................3
4.      Exercise of Options; Option Price....................................................5
5.      Withdrawal from the Plan.............................................................6
6.      Termination of Employment............................................................7
7.      Restriction upon Assignment..........................................................7
8.      No Rights of Stockholders until Shares Issued........................................7
9.      Changes in the Stock and Corporate Events; Adjustment of Options.....................8
10.     Use of Funds; No Interest Paid.......................................................9
11.     Dividends............................................................................9
12.     Amendment, Suspension or Termination of the Plan....................................10
13.     Administration by Committee; Rules and Regulations..................................10
14.     Designation of Subsidiary Corporations..............................................11
15.     No Rights as an Employee............................................................11
16.     Term; Approval by Stockholders......................................................11
17.     Effect upon Other Plans.............................................................11
18.     Conditions to Issuance of Stock Certificates........................................12
19.     Notification of Disposition.........................................................12
20.     Notices.............................................................................12
21.     Headings............................................................................13
</TABLE>



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                            ACLARA BIOSCIENCES, INC.

                          EMPLOYEE STOCK PURCHASE PLAN



        ACLARA BioSciences, Inc., a Delaware corporation (the "Company"), hereby
adopts the ACLARA BioSciences, Inc. Employee Stock Purchase Plan (the "Plan"),
effective as of _____________, 2000.

        The purposes of the Plan are as follows:

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

                (2) To help such employees provide for their future security and
        to encourage them to remain in the employment of the Company and its
        Subsidiary Corporations.

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

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

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

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

           (d) "Base Compensation" of an Eligible Employee shall mean the gross
base compensation received by such Eligible Employee on each Payday as
compensation for services to the Company or any Designated Subsidiary
Corporation, excluding overtime payments, sales commissions, incentive
compensation, bonuses, expense reimbursements, fringe benefits and other
special-payments.

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

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

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


<PAGE>   4

           (h) "Company" means ACLARA BioSciences, Inc., a Delaware corporation.

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

           (j) "Date of Grant" of any Option means the date on which such Option
is granted, which shall be the first day of the Offering Period with respect to
which the Option was granted, in accordance with Section 3(a).

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

           (l) "Effective Date" means the first day of the first Offering
Period, which shall be the date immediately preceding the first date on which a
share of Stock is traded on an exchange or quoted on Nasdaq or a successor
quotation system.

           (m) "Eligible Employee" means an Employee of the Company or any
Designated Subsidiary Corporation: (i) who does not, immediately after the
Option is granted, own (directly or through attribution) stock possessing five
percent (5%) or more of the total combined voting power or value of all classes
of Stock or other stock of the Company, a Parent Corporation or a Subsidiary
Corporation (as determined under Section 423(b)(3) of the Code); (ii) whose
customary employment is for more than twenty (20) hours per week; (iii) whose
customary employment is for more than five (5) months in any calendar year; and
(iv) who has been employed by the Company, any Parent Corporation and any
Subsidiary Corporation for not less than six (6) months. For purposes of
paragraph (i) above, the rules of Section 424(d) of the Code with regard to the
attribution of stock ownership shall apply in determining the stock ownership of
an individual, and stock which an Employee may purchase under outstanding
options shall be treated as stock owned by the Employee. During a leave of
absence meeting the requirements of Treasury Regulation Section 1.421-7(h)(2),
an individual shall be treated as an Employee of the Company or Subsidiary
Corporation employing such individual immediately prior to such leave.

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

           (o) "Offering Period" shall mean each six-month period commencing on
any November 1 and May 1 on or after the Effective Date; provided, however, that
the first Offering Period under the Plan shall be the period commencing on the
Effective Date and ending October 31, 2000. Options shall be granted on the Date
of Grant and exercised on the Date of Exercise, as provided in Sections 3(a) and
4(a), respectively.



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<PAGE>   5

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

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

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

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

           (t) "Plan" means the ACLARA BioSciences, Inc. Employee Stock Purchase
Plan.

           (u) "Stock" means the shares of the Company's Common Stock, $.001 par
value.

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

        2. STOCK SUBJECT TO THE PLAN. Subject to the provisions of Section 9
hereof (relating to adjustments upon changes in the Stock) and Section 12 hereof
(relating to amendments of the Plan), the Stock that may be sold pursuant to
Options granted under the Plan shall not exceed in the aggregate three hundred
thousand (300,000) shares of Stock. The shares of Stock sold pursuant to Options
granted under the Plan may be unissued shares or treasury shares of Stock, or
shares of Stock bought on the New York Stock Exchange or other
nationally-recognized exchange, or other market, for purposes of the Plan.

        3. GRANT OF OPTIONS.

           (a) Option Grants. The Company shall grant Options under the Plan to
all Eligible Employees in successive Offering Periods until the earlier of: (i)
the date on which the number of shares of Stock available under the Plan have
been sold, or (ii) the date on which the Plan is suspended or terminates. Each
Employee who is an Eligible Employee on the first day of an Offering Period
shall be granted an Option with respect to such Offering Period. The Date of
Grant of such an Option shall be the first day of the Offering Period with
respect to which such Option was granted. Each Option shall expire on the Date
of Exercise immediately after the automatic exercise of the Option in accordance
with Section 4(a), unless such Option terminates earlier in accordance with
Section 5, 6 or 9. The number of shares of Stock subject to an Eligible


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Employee's Option shall equal the cumulative payroll deductions authorized by
such Eligible Employee in accordance with subsection (b) for the Option Period
(if any), divided by the Option Price; provided, however, that the number of
shares of Stock subject to such Option shall not exceed five thousand (5,000)
shares; and, provided, further, that the number of shares of Stock subject to
such Option shall not exceed the number determined in accordance with subsection
(c). The Company shall not grant an Option with respect to an Offering Period to
any individual who is not an Eligible Employee on the first day of such Offering
Period.

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

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



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<PAGE>   7

(iii) a right to purchase Stock or other stock which has accrued under an Option
or other option may not be carried over to any Option or other option. This
limitation shall be applied in accordance with Section 423(b)(8) of the Code and
the Treasury Regulations thereunder.

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

        4. EXERCISE OF OPTIONS; OPTION PRICE.

           (a) Option Exercise. Each Employee automatically and without any act
on such Employee's part shall be deemed to have exercised such Employee's Option
on the Date of Exercise to the extent that the balance then in the Employee's
Account is sufficient to purchase, at the Option Price, shares of the Stock
subject to the Option (including fractional shares).

           (b) Option Price Defined. The option price per share of Stock (the
"Option Price") to be paid by an Employee upon the exercise of the Employee's
Option shall be equal to 85% of the lesser of: (i) the Fair Market Value of a
share of Stock on the Date of Exercise and (ii) the Fair Market Value of a share
of Stock on the Date of Grant. The Fair Market Value of a share of Stock as of a
given date shall be: (A) the closing price of a share of Stock on the principal
exchange on which the Stock is then trading, if any, on such date (or, if shares
of Stock were not traded on such date, then on the next preceding trading day
during which a sale occurred); (B) if the Stock is not traded on an exchange,
but is quoted on Nasdaq or a successor quotation system, (I) the last sales
price (if the Stock is then listed as a National Market Issue under the NASD
National Market System), or (II) the mean between the closing representative bid
and asked prices (in all other cases) for a share of Stock on such date (or, if
shares of Stock were not traded on such date, then on the next preceding trading
day during which a sale occurred) as reported by Nasdaq or such successor
quotation system; (iii) if the Stock is not publicly traded on an exchange and
not quoted on Nasdaq or a successor quotation system, the mean between the
closing bid and asked prices for a share of Stock on such date (or, if shares of
Stock were not traded on such date, then on the next preceding trading day
during which a sale occurred), as determined in good faith by the Committee; or
(iv) if the Stock is not publicly traded, the fair market value of a share of
Stock established by the Committee acting in good faith.

           (c) Book Entry/Share Certificates. As soon as practicable after the
purchase of shares of Stock upon the exercise of an Option by an Employee, the
Company shall issue the shares of Stock to such Employee and such shares shall
be held in the custody of the Agent for the benefit of the Employee. The Company
or the Agent shall make an entry on its books and records indicating that the
shares of Stock purchased in connection with such exercise (including any
partial share) have been duly issued as of that date to such Employee. An
Employee shall have the right at any time to request in writing a certificate or
certificates for all or a portion of the whole shares of Stock purchased
hereunder. Upon receipt of an Employee's written request



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<PAGE>   8

for any such certificate, the Company shall (or shall cause the Agent to),
within ten (10) days after the date of such receipt, deliver any such
certificate to the Employee; provided, however, that no certificate shall be
issued to an Employee with respect to Stock purchased hereunder until the
expiration of eighteen (18) months from the date of exercise of the Option to
purchase such Stock. Nothing in this subsection (c) shall prohibit the sale or
other disposition by an Employee of shares of Stock purchased hereunder. In the
event the Company is required to obtain authority from any commission or agency
to issue any certificate or certificates for all or a portion of the whole
shares of Stock purchased hereunder, the Company shall seek to obtain such
authority as soon as reasonably practicable.

           (d) Pro Rata Allocations. If the total number of shares of Stock for
which Options are to be exercised on any date exceeds the number of shares of
Stock remaining unsold under the Plan (after deduction for all shares of Stock
for which Options have theretofore been exercised), the Committee shall make a
pro rata allocation of the available remaining shares of Stock in as nearly a
uniform manner as shall be practicable and the balance of the amount credited to
the Account of each Employee which has not been applied to the purchase of
shares of Stock shall be paid to such Employee in one lump sum in cash within
thirty (30) days after the Date of Exercise, without any interest thereon.

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

        5. WITHDRAWAL FROM THE PLAN.

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

           (b) Eligibility following Withdrawal. An Employee who withdraws from
the Plan with respect to an Option Period, and who is still an Eligible
Employee, may elect to



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participate again in the Plan for any subsequent Offering Period by delivering
to the Company an Authorization pursuant to Section 3(b).

        6. TERMINATION OF EMPLOYMENT.

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

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

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

        8. NO RIGHTS OF STOCKHOLDERS UNTIL SHARES ISSUED. With respect to shares
of Stock subject to an Option, an Employee shall not be deemed to be a
stockholder of the Company, and the Employee shall not have any of the rights or
privileges of a stockholder, until such shares have been issued to the Employee
or his or her nominee following exercise of the Employee's Option. No
adjustments shall be made for dividends (ordinary or extraordinary, whether in
cash



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<PAGE>   10

securities, or other property) or distribution or other rights for which the
record date occurs prior to the date of such issuance, except as otherwise
expressly provided herein.

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

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

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

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

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

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

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

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



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<PAGE>   11

                (iii) To provide for either the purchase of any Option
        outstanding for an amount of cash equal to the amount that could have
        been obtained upon the exercise of such Option had such Option been
        currently exercisable, or the replacement of such Option with other
        rights or property selected by the Committee in its sole discretion;

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

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

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

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

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

        11. DIVIDENDS.

            (a) Cash dividends and other cash distributions received by the
Agent with respect to Stock held in its custody hereunder will be credited to
each Employee's Account in accordance with such Employee's interests in such
Stock, and shall be applied, as soon as practicable after the receipt thereof by
the Agent, to the purchase in the open market at prevailing market prices of the
number of whole shares of Stock that may be purchased with such funds (after
deductions of any bank service fees, brokerage charges, transfer taxes, and any
other



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<PAGE>   12

transaction fee, expense or cost payable in connection with the purchase of such
shares of Stock and not otherwise paid by the Employer.)

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

        12. AMENDMENT, SUSPENSION OR TERMINATION OF THE PLAN. The Board may
amend, suspend, or terminate the Plan at any time and from time to time,
provided that approval by a vote of the holders of the outstanding shares of the
Company's capital stock entitled to vote shall be required to amend the Plan to:
(a) change the number of shares of Stock that may be sold pursuant to Options
under the Plan, (b) alter the requirements for eligibility to participate in the
Plan, or (c) in any manner that would cause the Plan to no longer be an
"employee stock purchase plan" within the meaning of Section 423(b) of the Code.

        13. ADMINISTRATION BY COMMITTEE; RULES AND REGULATIONS.

            (a) Appointment of Committee. The Plan shall be administered by the
Committee, which shall be composed of not less than two members of the Board,
each of whom shall be a "non-employee director" within the meaning of Rule 16b-3
which has been adopted by the Securities and Exchange Commission under the
Securities Exchange Act of 1934, as amended. Each member of the Committee shall
serve for a term commencing on a date specified by the Board and continuing
until the member dies, resigns or is removed from office by the Board. The
Committee at its option may utilize the services of an agent to assist in the
administration of the Plan, including establishing and maintaining an individual
securities account under the Plan for each Employee.

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

            (c) Majority Rule. The Committee shall act by a majority of its
members in office. The Committee may act either by vote at a meeting or by a
memorandum or other written instrument signed by a majority of the Committee.



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<PAGE>   13

            (d) Compensation; Professional Assistance; Good Faith Actions. All
expenses and liabilities incurred by members of the Committee in connection with
the administration of the Plan shall be borne by the Company. The Committee may,
with the approval of the Board, employ attorneys, consultants, accountants,
appraisers, brokers or other persons. The Committee, the Company and its
officers and directors shall be entitled to rely upon the advice, opinions or
valuations of any such persons. All actions taken and all interpretations and
determinations made by the Committee in good faith shall be final and binding
upon all Employees, the Company and all other interested persons. No member of
the Committee shall be personally liable for any action, determination or
interpretation made in good faith with respect to the Plan or the Options, and
all members of the Committee shall be fully protected by the Company in respect
to any such action, determination, or interpretation.

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

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

        16. TERM; APPROVAL BY STOCKHOLDERS. Subject to approval by the
stockholders of the Company in accordance with this Section, the Plan shall be
in effect until May 1, 2010, unless sooner terminated in accordance with Section
12. No Option may be granted during any period of suspension of the Plan or
after termination of the Plan. The Plan shall be submitted for the approval of
the Company's stockholders within twelve (12) months after the date of the
adoption of the Plan by the Board. Options may be granted prior to such
stockholder approval; provided, however, that such Options shall not be
exercisable prior to the time when the Plan is approved by the Company's
stockholders; and, provided, further, that if such approval has not been
obtained by the end of said 12-month period, all Options previously granted
under the Plan shall thereupon terminate without being exercised.

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



                                       11
<PAGE>   14

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

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

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

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

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

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

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

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





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<PAGE>   15


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

                                  * * * * * * *

        I hereby certify that the ACLARA BioSciences, Inc. Employee Stock
Purchase Plan was adopted by the Board of Directors of ACLARA BioSciences, Inc.
on February 11, 2000.

        Executed at Mountain View, California on this ___th day of _______,
2000.





                                           ____________________________________
                                           ___________________________________
                                           Secretary


                                  * * * * * * *

        I hereby certify that the ACLARA BioSciences, Inc. Employee Stock
Purchase Plan was approved by the stockholders of ACLARA BioSciences, Inc. on
_________________, 2000.


        Executed at Mountain View, California on this ___th day of _______,
2000.



                                           ____________________________________
                                           ___________________________________
                                           Secretary





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