<PAGE>


                                                                     Exhibit 3.2
                              AMENDED AND RESTATED

                                     BYLAWS

                                       OF

                           ROSETTA INPHARMATICS, INC.


<PAGE>


                                TABLE OF CONTENTS
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ARTICLE I - CORPORATE OFFICES.....................................................................1

         1.1          Registered Office...........................................................1
         1.2          Other Offices...............................................................1

ARTICLE II - MEETINGS OF STOCKHOLDERS.............................................................1

         2.1          Place Of Meetings...........................................................1
         2.2          Annual Meeting..............................................................1
         2.3          Special Meeting.............................................................2
         2.4          Notice Of Stockholders'Meetings.............................................2
         2.5          Advance Notice of Stockholder Nominees and Other Stockholder................3
         2.6          Quorum......................................................................4
         2.7          Adjourned Meeting; Notice...................................................4
         2.8          Conduct Of Business.........................................................4
         2.9          Voting......................................................................5
         2.10         Waiver Of Notice ...........................................................5
         2.11         Record Date For Stockholder Notice; Voting .................................5
         2.12         Proxies.....................................................................6

ARTICLE III - DIRECTORS...........................................................................6

         3.1          Powers......................................................................6
         3.2          Number Of Directors.........................................................6
         3.3          Election, Qualification And Term Of Office Of Directors.....................6
         3.4          Resignation And Vacancies...................................................7
         3.5          Place Of Meetings; Meetings By Telephone....................................8
         3.6          Regular Meetings............................................................8
         3.7          Special Meetings; Notice....................................................8
         3.8          Quorum......................................................................8
         3.9          Waiver Of Notice............................................................9
         3.10         Board Action By Written Consent Without A Meeting...........................9
         3.11         Fees And Compensation Of Directors..........................................9
         3.12         Approval Of Loans To Officers...............................................9
         3.13         Removal Of Directors.......................................................10
         3.14         Chairman Of The Board Of Directors.........................................10

ARTICLE IV - COMMITTEES..........................................................................10

         4.1          Committees Of Directors....................................................10
         4.2          Committee Minutes..........................................................11
         4.3          Meetings And Action Of Committees..........................................11

ARTICLE V - OFFICERS  ...........................................................................12

         5.1          Officers...................................................................12
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                               TABLE OF CONTENTS
                                   (CONTINUED)


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         5.2          Appointment Of Officers....................................................12
         5.3          Subordinate Officers.......................................................12
         5.4          Removal And Resignation Of Officers........................................12
         5.5          Vacancies In Offices.......................................................12
         5.6          Chief Executive Officer....................................................13
         5.7          President..................................................................13
         5.8          Vice Presidents............................................................13
         5.9          Secretary..................................................................13
         5.10         Chief Financial Officer....................................................14
         5.11         Representation Of Shares Of Other Corporations.............................14
         5.12         Authority And Duties Of Officers...........................................14

ARTICLE VI - INDEMNIFICATION OF DIRECTORS, OFFICERS, EMPLOYEES, AND OTHER AGENTS.................15

         6.1          Indemnification Of Directors And Officers..................................15
         6.2          Indemnification Of Others..................................................15
         6.3          Payment Of Expenses In Advance.............................................15
         6.4          Indemnity Not Exclusive....................................................16
         6.5          Insurance..................................................................16
         6.6          Conflicts..................................................................16

ARTICLE VII - RECORDS AND REPORTS................................................................16

         7.1          Maintenance And Inspection Of Records......................................16
         7.2          Inspection By Directors....................................................17
         7.3          Annual Statement To Stockholders...........................................17

ARTICLE VIII - GENERAL MATTERS...................................................................17

         8.1          Checks.....................................................................17
         8.2          Execution Of Corporate Contracts And Instruments...........................17
         8.3          Stock Certificates; Partly Paid Shares.....................................18
         8.4          Special Designation On Certificates........................................18
         8.5          Lost Certificates..........................................................19
         8.6          Construction; Definitions..................................................19
         8.7          Dividends..................................................................19
         8.8          Fiscal Year................................................................19
         8.9          Seal.......................................................................19
         8.10         Transfer Of Stock..........................................................20
         8.11         Stock Transfer Agreements..................................................20
         8.12         Registered Stockholders....................................................20
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                               TABLE OF CONTENTS
                                   (CONTINUED)

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ARTICLE IX - AMENDMENTS..........................................................................20
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                                      -4-
<PAGE>



                              AMENDED AND RESTATED

                                     BYLAWS

                                       OF

                           ROSETTA INPHARMATICS, INC.

                                    ARTICLE I

                                CORPORATE OFFICES

         1.1      REGISTERED OFFICE.

                  The registered office of the corporation shall be in the City
of Dover, County of Kent, State of Delaware. The name of the registered agent of
the corporation at such location is National Corporate Research, Ltd.

         1.2      OTHER OFFICES.

                  The Board of Directors may at any time establish other offices
at any place or places where the corporation is qualified to do business.

                                   ARTICLE II

                            MEETINGS OF STOCKHOLDERS

         2.1      PLACE OF MEETINGS.

                  Meetings of stockholders shall be held at any place, within or
outside the State of Delaware, designated by the Board of Directors. In the
absence of any such designation, stockholders' meetings shall be held at the
registered office of the corporation.

         2.2      ANNUAL MEETING.

                  (a)      The annual meeting of stockholders shall be held on
such date, time and place, either within or without the State of Delaware, as
may be designated by resolution of the Board of Directors each year. At the
meeting, directors shall be elected and any other proper business may be
transacted.

                  (b)      Nominations of persons for election to the Board of
Directors of the Corporation and the proposal of business to be transacted by
the stockholders may be made at an annual meeting of stockholders (i) pursuant
to the Corporation's notice with respect to such meeting, (ii) by or at the
direction of the Board of Directors or (iii) by any stockholder of the
Corporation who was a stockholder of record at the time of giving of the notice
provided for in this Section 2.2, who is entitled to vote at the meeting and who
has complied with the notice procedures set forth in this Section 2.2.


<PAGE>


                  (c)      For nominations or other business to be properly
brought before an annual meeting by a stockholder pursuant to clause (iii) of
paragraph (b) of this Section 2.2, the stockholder must have given timely notice
thereof in writing to the secretary of the Corporation, as provided in Section
2.5, and such business must be a proper matter for stockholder action under the
General Corporation Law of Delaware.

                  (d)      Only such business shall be conducted at an annual
meeting of stockholders as shall have been brought before the meeting in
accordance with the procedures set forth in these Bylaws. The chairman of the
meeting shall determine whether a nomination or any business proposed to be
transacted by the stockholders has been properly brought before the meeting and,
if any proposed nomination or business has not been properly brought before the
meeting, the chairman shall declare that such proposed business or nomination
shall not be presented for stockholder action at the meeting.

                  (e)      Nothing in this Section 2.2 shall be deemed to affect
any rights of stockholders to request inclusion of proposals in the
Corporation's proxy statement pursuant to Rule 14a-8 under the Exchange Act.

         2.3      SPECIAL MEETING.

                  A special meeting of the stockholders may be called at any
time by the Board of Directors, the chairman of the board, the president or by
one or more stockholders holding shares in the aggregate entitled to cast not
less than twenty-five (25) percent of the votes at that meeting.

         2.4      NOTICE OF STOCKHOLDERS' MEETINGS; AFFIDAVIT OF NOTICE.

                  All notices of meetings of stockholders shall be in writing
and shall be sent or otherwise given in accordance with this Section 2.4 of
these Bylaws not less than 10 nor more than 60 days before the date of the
meeting to each stockholder entitled to vote at such meeting (or such longer or
shorter time as is required by Section 2.5 of these Bylaws, if applicable). The
notice shall specify the place, date, and hour of the meeting, and, in the case
of a special meeting, the purpose or purposes for which the meeting is called.

                  Written notice of any meeting of stockholders, if mailed, is
given when deposited in the United States mail, postage prepaid, directed to the
stockholder at his address as it appears on the records of the Corporation. An
affidavit of the secretary or an assistant secretary or of the transfer agent of
the Corporation that the notice has been given shall, in the absence of fraud,
be prima facie evidence of the facts stated therein.

         2.5      ADVANCE NOTICE OF STOCKHOLDER NOMINEES AND OTHER STOCKHOLDER
                  PROPOSALS.

                  (a)      Only persons who are nominated in accordance with the
procedures set forth in this Section 2.5 shall be eligible for election as
directors. Nominations of persons for election to the Board of Directors of the
Corporation may be made at a meeting of stockholders by or at the direction of
the Board of Directors or by any stockholder of the Corporation entitled to vote
for the election of directors at the meeting who complies with the notice
procedures set


                                      -2-
<PAGE>

forth in this Section 2.5. Such nominations, other than those made by or at
the direction of the Board of Directors, shall be made pursuant to timely
notice in writing to the secretary of the Corporation. Stockholders may bring
other business before the annual meeting, provided that timely notice is
provided to the secretary of the Corporation in accordance with this section,
and provided further that such business is a proper matter for stockholder
action under the General Corporation Law of Delaware. To be timely, a
stockholder's notice shall be delivered to or mailed and received at the
principal executive offices of the Corporation not less than 90 days nor more
than 120 days prior to the anniversary date of the prior year's meeting;
provided, however, that in the event that (i) the date of the annual meeting
is more than 30 days prior to or more than 60 days after such anniversary
date, and (ii) less than 60 days notice or prior public disclosure of the
date of the meeting is given or made to stockholders, notice by the
stockholder to be timely must be so received not later than the close of
business on the 10th day following the day on which such notice of the date
of the meeting was mailed or such public disclosure was made. Such
stockholder's notice shall set forth (a) as to each person whom the
stockholder proposes to nominate for election or re-election as a directors,
(i) the name, age, business address and residence address of such person,
(ii) the principal occuption or employment of such person, (iii) the class
and number of shares of the Corporation which are beneficially owned by such
person and (iv) any other information relating to such person that is
required to be disclosed in solicitations of proxies for election of
directors, or is otherwise required, in each case pursuant to Regulation 14A
under the Securities Exchange Act of 1934 (including, without limitation,
such person's written consent to being name in the proxy statement as a
nominee and to serving as a director if elected); (b) as to any other
business that the stockholder proposes to bring before the meeting, a brief
description of such business, the reasons for conducting such business at the
meeting and any material interest in such business of such stockholder and
the beneficial owner, if any, on whose behalf the proposal is made; and (c)
as to the stockholder giving the notice and the beneficial owner, if any, on
whose behalf the proposal is made (i) the name and address of the
stockholder, as they appear on the Corporation's books, and of such
beneficial owner and (ii) the class and number of shares of the Corporation
which are owned of record by such stockholder and beneficially by such
beneficial owner. At the request of the Board of Directors any person
nominated by the Board of Directors for election as a director shall furnish
to the secretary of the Corporation that information required to be set forth
in a stockholder's notice of nomination which pertains to the nominee. The
chairman of the meeting shall, if the facts warrant, determine and declare to
the meeting that a nomination was not made in accordance with the procedures
prescribed by the Bylaws, and if he or she should so determine, he or she
shall so declare to the meeting and the defective nomination shall be
disregarded.

                  (b)      If a special meeting is called by any person or
persons other than the Board of Directors, the president or the chairman of the
board, the request shall be in writing, specifying the time of such meeting and
the general nature of the business proposed to be transacted, and shall be
delivered personally or sent by registered mail or by telegraphic or other
facsimile transmission to the chairman of the board, the president, any vice
president, or the secretary of the corporation. No business may be transacted at
such special meeting otherwise than specified in such notice. The officer
receiving the request shall cause notice to be promptly given to the
stockholders entitled to vote, in accordance with the provisions of Sections 2.4
and 2.5 of this Article II, that a meeting will be held at the time requested by
the person or persons


                                      -3-
<PAGE>


calling the meeting, not less than thirty-five (35) nor more than sixty (60)
days after the receipt of the request. If the notice is not given within twenty
(20) days after the receipt of the request, the person or persons requesting the
meeting may give the notice. Nothing contained in this paragraph of this Section
2.3 shall be construed as limiting, fixing, or affecting the time when a meeting
of stockholders called by action of the Board of Directors may be held.

         2.6      QUORUM.

                  The holders of a majority of the stock issued and outstanding
and entitled to vote thereat, present in person or represented by proxy, shall
constitute a quorum at all meetings of the stockholders for the transaction of
business except as otherwise provided by statute or by the certificate of
incorporation. If, however, such quorum is not present or represented at any
meeting of the stockholders, then either (a) the chairman of the meeting or (b)
the stockholders entitled to vote thereat, present in person or represented by
proxy, shall have power to adjourn the meeting from time to time, without notice
other than announcement at the meeting, until a quorum is present or
represented. At such adjourned meeting at which a quorum is present or
represented, any business may be transacted that might have been transacted at
the meeting as originally noticed.

         2.7      ADJOURNED MEETING; NOTICE.

                  When a meeting is adjourned to another time or place, unless
these Bylaws otherwise require, notice need not be given of the adjourned
meeting if the time and place thereof are announced at the meeting at which the
adjournment is taken. At the adjourned meeting the corporation may transact any
business that might have been transacted at the original meeting. If the
adjournment is for more than thirty (30) days, or if after the adjournment a new
record date is fixed for the adjourned meeting, a notice of the adjourned
meeting shall be given to each stockholder of record entitled to vote at the
meeting.

         2.8      CONDUCT OF BUSINESS.

                  The chairman of any meeting of stockholders shall determine
the order of business and the procedure at the meeting, including the manner of
voting and the conduct of business.

         2.9      VOTING.

                  The stockholders entitled to vote at any meeting of
stockholders shall be determined in accordance with the provisions of Section
2.11 of these Bylaws, subject to the provisions of Sections 217 and 218 of the
General Corporation Law of Delaware (relating to voting rights of fiduciaries,
pledgors and joint owners of stock and to voting trusts and other voting
agreements).

                  Except as may be otherwise provided in the certificate of
incorporation, each stockholder shall be entitled to one vote for each share of
capital stock held by such stockholder.


                                      -4-
<PAGE>


         2.10     WAIVER OF NOTICE.

                  Whenever notice is required to be given under any provision of
the General Corporation Law of Delaware or of the certificate of incorporation
or these Bylaws, a written waiver thereof, signed by the person entitled to
notice, whether before or after the time stated therein, shall be deemed
equivalent to notice. Attendance of a person at a meeting shall constitute a
waiver of notice of such meeting, except when the person attends a meeting for
the express purpose of objecting, at the beginning of the meeting, to the
transaction of any business because the meeting is not lawfully called or
convened. Neither the business to be transacted at, nor the purpose of, any
regular or special meeting of the stockholders need be specified in any written
waiver of notice unless so required by the certificate of incorporation or these
Bylaws.

         2.11     RECORD DATE FOR STOCKHOLDER NOTICE; VOTING.

                  In order that the corporation may determine the stockholders
entitled to notice of or to vote at any meeting of stockholders or any
adjournment thereof, or entitled to receive payment of any dividend or other
distribution or allotment of any rights, or entitled to exercise any rights in
respect of any change, conversion or exchange of stock or for the purpose of any
other lawful action, the Board of Directors may fix, in advance, a record date,
which shall not be more than sixty (60) nor less than ten (10) days before the
date of such meeting, nor more than sixty (60) days prior to any other action.

                  If the Board of Directors does not so fix a record date:

                  (a)      The record date for determining stockholders entitled
to notice of or to vote at a meeting of stockholders shall be at the close of
business on the day next preceding the day on which notice is given, or, if
notice is waived, at the close of business on the day next preceding the day on
which the meeting is held.

                  (b)      The record date for determining stockholders for any
other purpose shall be at the close of business on the day on which the Board of
Directors adopts the resolution relating thereto.

                  A determination of stockholders of record entitled to notice
of or to vote at a meeting of stockholders shall apply to any adjournment of the
meeting; provided, however, that the Board of Directors may fix a new record
date for the adjourned meeting.

         2.12     PROXIES.

                  Each stockholder entitled to vote at a meeting of stockholders
may authorize another person or persons to act for such stockholder by a written
proxy, signed by the stockholder and filed with the secretary of the
corporation, but no such proxy shall be voted or acted upon after three (3)
years from its date, unless the proxy provides for a longer period. A proxy
shall be deemed signed if the stockholder's name is placed on the proxy (whether
by manual signature, typewriting, electronic transmission or otherwise) by the
stockholder or the stockholder's attorney-in-fact. The revocability of a proxy
that states on its face that it is


                                      -5-
<PAGE>


irrevocable shall be governed by the provisions of Section 212(e) of the General
Corporation Law of Delaware.

                                   ARTICLE III

                                    DIRECTORS

         3.1      POWERS.

                  Subject to the provisions of the General Corporation Law of
Delaware and any limitations in the certificate of incorporation or these Bylaws
relating to action required to be approved by the stockholders or by the
outstanding shares, the business and affairs of the corporation shall be managed
and all corporate powers shall be exercised by or under the direction of the
Board of Directors.

         3.2      NUMBER OF DIRECTORS.

                  Upon the adoption of these bylaws, the number of directors
constituting the entire Board of Directors shall be eight. Thereafter, this
number may be changed by a resolution of the Board of Directors or of the
stockholders, subject to Section 3.4 of these Bylaws. No reduction of the
authorized number of directors shall have the effect of removing any director
before such director's term of office expires.

         3.3      ELECTION, QUALIFICATION AND TERM OF OFFICE OF DIRECTORS.

                  Except as provided in Section 3.4 of these Bylaws and unless
otherwise provided in the certificate of incorporation, directors shall be
elected at each annual meeting of stockholders to hold office until the next
annual meeting.

                  Directors need not be stockholders unless so required by the
certificate of incorporation or these Bylaws, wherein other qualifications for
directors may be prescribed. Each director, including a director elected to fill
a vacancy, shall hold office until his or her successor is elected and qualified
or until his or her earlier resignation or removal.

                  Elections of directors need not be by written ballot.

         3.4      RESIGNATION AND VACANCIES.

                  Any director may resign at any time upon written notice to the
attention of the Secretary of the corporation. When one or more directors so
resigns and the resignation is effective at a future date, a majority of the
directors then in office, including those who have so resigned, shall have power
to fill such vacancy or vacancies, the vote thereon to take effect when such
resignation or resignations shall become effective, and each director so chosen
shall hold office as provided in this section in the filling of other vacancies,
unless otherwise provided in the certificate of incorporation and subject to the
rights of any holders of preferred stock then outstanding.


                                      -6-
<PAGE>


                  Unless otherwise provided in the certificate of incorporation
or these Bylaws:

                  (a)      Vacancies and newly created directorships resulting
from any increase in the authorized number of directors elected by all of the
stockholders having the right to vote as a single class may be filled by a
majority of the directors then in office, although less than a quorum, or by a
sole remaining director.

                  (b)      Whenever the holders of any class or classes of stock
or series thereof are entitled to elect one or more directors by the provisions
of the certificate of incorporation, vacancies and newly created directorships
of such class or classes or series may be filled by a majority of the directors
elected by such class or classes or series thereof then in office, or by a sole
remaining director so elected.

                  If at any time, by reason of death or resignation or other
cause, the corporation should have no directors in office, then any officer or
any stockholder or an executor, administrator, trustee or guardian of a
stockholder, or other fiduciary entrusted with like responsibility for the
person or estate of a stockholder, may call a special meeting of stockholders in
accordance with the provisions of the certificate of incorporation or these
Bylaws, or may apply to the Court of Chancery for a decree summarily ordering an
election as provided in Section 211 of the General Corporation Law of Delaware.

                  If, at the time of filling any vacancy or any newly created
directorship, the directors then in office constitute less than a majority of
the whole board (as constituted immediately prior to any such increase), then
the Court of Chancery may, upon application of any stockholder or stockholders
holding at least ten (10) percent of the total number of the shares at the time
outstanding having the right to vote for such directors, summarily order an
election to be held to fill any such vacancies or newly created directorships,
or to replace the directors chosen by the directors then in office as aforesaid,
which election shall be governed by the provisions of Section 211 of the General
Corporation Law of Delaware as far as applicable.

         3.5      PLACE OF MEETINGS; MEETINGS BY TELEPHONE.

                  The Board of Directors of the corporation may hold meetings,
both regular and special, either within or outside the State of Delaware.

                  Unless otherwise restricted by the certificate of
incorporation or these Bylaws, members of the Board of Directors, or any
committee designated by the Board of Directors, may participate in a meeting of
the Board of Directors, or any committee, by means of conference telephone or
similar communications equipment by means of which all persons participating in
the meeting can hear each other, and such participation in a meeting shall
constitute presence in person at the meeting.

         3.6      REGULAR MEETINGS.

                  Regular meetings of the Board of Directors may be held without
notice at such time and at such place as shall from time to time be determined
by the board in accordance with the proposed schedule approved by the Board of
Directors, as amended from time to time.


                                      -7-
<PAGE>


         3.7      SPECIAL MEETINGS; NOTICE.

                  Special meetings of the Board of Directors for any purpose or
purposes may be called at any time by the chairman of the board, the president,
any vice president, the secretary or any two directors.

                  Notice of the time and place of special meetings shall be
delivered personally or by telephone to each director or sent by first-class
mail or telegram, charges prepaid, addressed to each director at that director's
address as it is shown on the records of the corporation. If the notice is
mailed, it shall be deposited in the United States mail at least four (4) days
before the time of the holding of the meeting. If the notice is delivered
personally or by telephone or by telegram, it shall be delivered personally or
by telephone or to the telegraph company at least forty-eight (48) hours before
the time of the holding of the meeting. Any oral notice given personally or by
telephone may be communicated either to the director or to a person at the
office of the director who the person giving the notice has reason to believe
will promptly communicate it to the director. The notice need not specify the
purpose or the place of the meeting, if the meeting is to be held at the
principal executive office of the corporation.

         3.8      QUORUM.

                  At all meetings of the Board of Directors, a majority of the
authorized number of directors shall constitute a quorum for the transaction of
business and the act of a majority of the directors present at any meeting at
which there is a quorum shall be the act of the Board of Directors, except as
may be otherwise specifically provided by statute or by the certificate of
incorporation. If a quorum is not present at any meeting of the Board of
Directors, then the directors present thereat may adjourn the meeting from time
to time, without notice other than announcement at the meeting, until a quorum
is present.

                  A meeting at which a quorum is initially present may continue
to transact business notwithstanding the withdrawal of directors, if any action
taken is approved by at least a majority of the required quorum for that
meeting.

         3.9      WAIVER OF NOTICE.

                  Whenever notice is required to be given under any provision of
the General Corporation Law of Delaware or of the certificate of incorporation
or these Bylaws, a written waiver thereof, signed by the person entitled to
notice, whether before or after the time stated therein, shall be deemed
equivalent to notice. Attendance of a person at a meeting shall constitute a
waiver of notice of such meeting, except when the person attends a meeting for
the express purpose of objecting, at the beginning of the meeting, to the
transaction of any business because the meeting is not lawfully called or
convened. Neither the business to be transacted at, nor the purpose of, any
regular or special meeting of the directors, or members of a committee of
directors, need be specified in any written waiver of notice unless so required
by the certificate of incorporation or these Bylaws.


                                      -8-
<PAGE>


         3.10     BOARD ACTION BY WRITTEN CONSENT WITHOUT A MEETING.

                  Unless otherwise restricted by the certificate of
incorporation or these Bylaws, any action required or permitted to be taken at
any meeting of the Board of Directors, or of any committee thereof, may be taken
without a meeting if all members of the board or committee, as the case may be,
consent thereto in writing and the writing or writings are filed with the
minutes of proceedings of the board or committee. Written consents representing
actions taken by the board or committee may be executed by telex, telecopy or
other facsimile transmission, and such facsimile shall be valid and binding to
the same extent as if it were an original.

         3.11     FEES AND COMPENSATION OF DIRECTORS.

                  Unless otherwise restricted by the certificate of
incorporation or these Bylaws, the Board of Directors shall have the authority
to fix the compensation of directors. No such compensation shall preclude any
director from serving the corporation in any other capacity and receiving
compensation therefor.

         3.12     APPROVAL OF LOANS TO OFFICERS.

                  The corporation may lend money to, or guarantee any obligation
of, or otherwise assist any officer or other employee of the corporation or of
its subsidiary, including any officer or employee who is a director of the
corporation or its subsidiary, whenever, in the judgment of the directors, such
loan, guaranty or assistance may reasonably be expected to benefit the
corporation. The loan, guaranty or other assistance may be with or without
interest and may be unsecured, or secured in such manner as the Board of
Directors shall approve, including, without limitation, a pledge of shares of
stock of the corporation. Nothing in this section contained shall be deemed to
deny, limit or restrict the powers of guaranty or warranty of the corporation at
common law or under any statute.

         3.13     REMOVAL OF DIRECTORS.

                  Unless otherwise restricted by statute, by the certificate of
incorporation or by these Bylaws, any director or the entire Board of Directors
may be removed, with or without cause, by the holders of a majority of the
shares then entitled to vote at an election of directors; provided, however,
that if the stockholders of the corporation are entitled to cumulative voting,
if less than the entire Board of Directors is to be removed, no director may be
removed without cause if the votes cast against his removal would be sufficient
to elect him if then cumulatively voted at an election of the entire Board of
Directors.

                  No reduction of the authorized number of directors shall have
the effect of removing any director prior to the expiration of such director's
term of office.

         3.14     CHAIRMAN OF THE BOARD OF DIRECTORS.

                  The corporation may also have, at the discretion of the Board
of Directors, a chairman of the Board of Directors who shall not be considered
an officer of the corporation.


                                      -9-
<PAGE>


                                   ARTICLE IV

                                   COMMITTEES

         4.1      COMMITTEES OF DIRECTORS.

         The Board of Directors may designate one or more committees, each
committee to consist of one or more of the directors of the corporation. The
Board may designate 1 or more directors as alternate members of any committee,
who may replace any absent or disqualified member at any meeting of the
committee. In the absence or disqualification of a member of a committee, the
member or members present at any meeting and not disqualified from voting,
whether or not such member or members constitute a quorum, may unanimously
appoint another member of the Board of Directors to act at the meeting in the
place of any such absent or disqualified member. Any such committee, to the
extent provided in the resolution of the Board of Directors, or in these Bylaws,
shall have and may exercise all the powers and authority of the Board of
Directors in the management of the business and affairs of the corporation, and
may authorize the seal of the corporation to be affixed to all papers which may
require it; but no such committee shall have the power or authority to (a) amend
the Certificate of Incorporation (except that a committee may, to the extent
authorized in the resolution or resolutions providing for the issuance of shares
of stock adopted by the Board of Directors as provided in Section 151(a) of the
General Corporation Law of Delaware, fix the designations and any of the
preferences or rights of such shares relating to dividends, redemption,
dissolution, any distribution of assets of the Corporation or the conversion
into, or the exchange of such shares for, shares of any other class or classes
or any other series of the same or any other class or classes of stock of the
Corporation or fix the number of shares of any series of stock or authorize the
increase or decrease of the shares of any series), (b) adopt an agreement of
merger or consolidation under Sections 251 or 252 of the General Corporation Law
of Delaware, (c) recommend to the stockholders the sale, lease or exchange of
all or substantially all of the Corporation's property and assets, (d) recommend
to the stockholders a dissolution of the Corporation or a revocation of a
dissolution, or (e) amend the Bylaws of the Corporation; and, unless the board
resolution establishing the committee, the Bylaws or the Certificate of
Incorporation expressly so provide, no such committee shall have the power or
authority to declare a dividend, to authorize the issuance of stock, or to adopt
a certificate of ownership and merger pursuant to Section 253 of the General
Corporation Law of Delaware.

                  4.2      COMMITTEE MINUTES.

                  Each committee shall keep regular minutes of its meetings and
report the same to the Board of Directors when required.

         4.3      MEETINGS AND ACTION OF COMMITTEES.

                  Meetings and actions of committees shall be governed by, and
held and taken in accordance with, the provisions of Section 3.5 (place of
meetings and meetings by telephone), Section 3.6 (regular meetings), Section 3.7
(special meetings and notice), Section 3.8 (quorum), Section 3.9 (waiver of
notice), and Section 3.10 (action without a meeting) of these Bylaws, with


                                      -10-
<PAGE>


such changes in the context of such provisions as are necessary to substitute
the committee and its members for the Board of Directors and its members;
provided, however, that the time of regular meetings of committees may be
determined either by resolution of the Board of Directors or by resolution of
the committee, that special meetings of committees may also be called by
resolution of the Board of Directors and that notice of special meetings of
committees shall also be given to all alternate members, who shall have the
right to attend all meetings of the committee. The Board of Directors may adopt
rules for the government of any committee not inconsistent with the provisions
of these Bylaws.

                                    ARTICLE V

                                    OFFICERS

         5.1      OFFICERS.

                  The officers of the corporation shall be a chief executive
officer, a president, a secretary, and a chief financial officer. The
corporation may also have, at the discretion of the Board of Directors, one or
more vice presidents, one or more assistant secretaries, one or more assistant
treasurers, and any such other officers as may be appointed in accordance with
the provisions of Section 5.3 of these Bylaws. Any number of offices may be held
by the same person.

         5.2      APPOINTMENT OF OFFICERS.

                  The officers of the corporation, except such officers as may
be appointed in accordance with the provisions of Sections 5.3 or 5.5 of these
Bylaws, shall be appointed by the Board of Directors, subject to the rights, if
any, of an officer under any contract of employment.

         5.3      SUBORDINATE OFFICERS.

                  The Board of Directors may appoint, or empower the chief
executive officer or the president to appoint, such other officers and agents as
the business of the corporation may require, each of whom shall hold office for
such period, have such authority, and perform such duties as are provided in
these Bylaws or as the Board of Directors may from time to time determine.

         5.4      REMOVAL AND RESIGNATION OF OFFICERS.

                  Subject to the rights, if any, of an officer under any
contract of employment, any officer may be removed, either with or without
cause, by an affirmative vote of the majority of the Board of Directors at any
regular or special meeting of the board or, except in the case of an officer
chosen by the Board of Directors, by any officer upon whom such power of removal
may be conferred by the Board of Directors.

                  Any officer may resign at any time by giving written notice to
the attention of the Secretary of the corporation. Any resignation shall take
effect at the date of the receipt of that


                                      -11-
<PAGE>


notice or at any later time specified in that notice; and, unless otherwise
specified in that notice, the acceptance of the resignation shall not be
necessary to make it effective. Any resignation is without prejudice to the
rights, if any, of the corporation under any contract to which the officer is a
party.

         5.5      VACANCIES IN OFFICES.

                  Any vacancy occurring in any office of the corporation shall
be filled by the Board of Directors.

         5.6      CHIEF EXECUTIVE OFFICER.

                  Subject to such supervisory powers, if any, as may be given by
the Board of Directors to the chairman of the board, if any, the chief executive
officer of the corporation shall, subject to the control of the Board of
Directors, have general supervision, direction, and control of the business and
the officers of the corporation. He or she shall preside at all meetings of the
stockholders and, in the absence or nonexistence of a chairman of the board, at
all meetings of the Board of Directors and shall have the general powers and
duties of management usually vested in the office of chief executive officer of
a corporation and shall have such other powers and duties as may be prescribed
by the Board of Directors or these bylaws.

         5.7      PRESIDENT.

                  Subject to such supervisory powers, if any, as may be given by
the Board of Directors to the chairman of the board (if any) or the chief
executive officer, the president shall have general supervision, direction, and
control of the business and other officers of the corporation. He or she shall
have the general powers and duties of management usually vested in the office of
president of a corporation and such other powers and duties as may be prescribed
by the Board of Directors or these Bylaws.

         5.8      VICE PRESIDENTS.

                  In the absence or disability of the chief executive officer
and president, the vice presidents, if any, in order of their rank as fixed by
the Board of Directors or, if not ranked, a vice president designated by the
Board of Directors, shall perform all the duties of the president and when so
acting shall have all the powers of, and be subject to all the restrictions
upon, the president. The vice presidents shall have such other powers and
perform such other duties as from time to time may be prescribed for them
respectively by the Board of Directors, these Bylaws, the president or the
chairman of the board.

         5.9      SECRETARY.

                  The secretary shall keep or cause to be kept, at the principal
executive office of the corporation or such other place as the Board of
Directors may direct, a book of minutes of all meetings and actions of
directors, committees of directors, and stockholders. The minutes shall show the
time and place of each meeting, the names of those present at directors'
meetings or


                                      -12-
<PAGE>


committee meetings, the number of shares present or represented at stockholders'
meetings, and the proceedings thereof.

                  The secretary shall keep, or cause to be kept, at the
principal executive office of the corporation or at the office of the
corporation's transfer agent or registrar, as determined by resolution of the
Board of Directors, a share register, or a duplicate share register, showing the
names of all stockholders and their addresses, the number and classes of shares
held by each, the number and date of certificates evidencing such shares, and
the number and date of cancellation of every certificate surrendered for
cancellation.

                  The secretary shall give, or cause to be given, notice of all
meetings of the stockholders and of the Board of Directors required to be given
by law or by these Bylaws. He or she shall keep the seal of the corporation, if
one be adopted, in safe custody and shall have such other powers and perform
such other duties as may be prescribed by the Board of Directors or by these
Bylaws.

         5.10     CHIEF FINANCIAL OFFICER.

                  The chief financial officer shall keep and maintain, or cause
to be kept and maintained, adequate and correct books and records of accounts of
the properties and business transactions of the corporation, including accounts
of its assets, liabilities, receipts, disbursements, gains, losses, capital
retained earnings, and shares. The books of account shall at all reasonable
times be open to inspection by any director.

                  The chief financial officer shall deposit all moneys and other
valuables in the name and to the credit of the corporation with such
depositories as may be designated by the Board of Directors. He or she shall
disburse the funds of the corporation as may be ordered by the Board of
Directors, shall render to the president, the chief executive officer, or the
directors, upon request, an account of all his or her transactions as chief
financial officer and of the financial condition of the corporation, and shall
have other powers and perform such other duties as may be prescribed by the
Board of Directors or these Bylaws.

         5.11     REPRESENTATION OF SHARES OF OTHER CORPORATIONS.

                  The chairman of the board, the chief executive officer, the
president, any vice president, the chief financial officer, the secretary or
assistant secretary of this corporation, or any other person authorized by the
Board of Directors or the chief executive officer or the president or a vice
president, is authorized to vote, represent, and exercise on behalf of this
corporation all rights incident to any and all shares of any other corporation
or corporations standing in the name of this corporation. The authority granted
herein may be exercised either by such person directly or by any other person
authorized to do so by proxy or power of attorney duly executed by the person
having such authority.


                                      -13-
<PAGE>


         5.12     AUTHORITY AND DUTIES OF OFFICERS.

                  In addition to the foregoing authority and duties, all
officers of the corporation shall respectively have such authority and perform
such duties in the management of the business of the corporation as may be
designated from time to time by the Board of Directors or the stockholders.

                                   ARTICLE VI

          INDEMNIFICATION OF DIRECTORS, OFFICERS, EMPLOYEES, AND OTHER
                                     AGENTS

         6.1      INDEMNIFICATION OF DIRECTORS AND OFFICERS.

                  The corporation shall, to the maximum extent and in the manner
permitted by the General Corporation Law of Delaware, indemnify each of its
directors and officers against expenses (including attorneys' fees), judgments,
fines, settlements and other amounts actually and reasonably incurred in
connection with any proceeding, arising by reason of the fact that such person
is or was an agent of the corporation. For purposes of this Section 6.1, a
"director" or "officer" of the corporation includes any person (a) who is or was
a director or officer of the corporation, (b) who is or was serving at the
request of the corporation as a director or officer of another corporation,
partnership, joint venture, trust or other enterprise, or (c) who was a director
or officer of a corporation which was a predecessor corporation of the
corporation or of another enterprise at the request of such predecessor
corporation.

         6.2      INDEMNIFICATION OF OTHERS.

                  The corporation shall have the power, to the maximum extent
and in the manner permitted by the General Corporation Law of Delaware, to
indemnify each of its employees and agents (other than directors and officers)
against expenses (including attorneys' fees), judgments, fines, settlements and
other amounts actually and reasonably incurred in connection with any
proceeding, arising by reason of the fact that such person is or was an agent of
the corporation. For purposes of this Section 6.2, an "employee" or "agent" of
the corporation (other than a director or officer) includes any person (a) who
is or was an employee or agent of the corporation, (b) who is or was serving at
the request of the corporation as an employee or agent of another corporation,
partnership, joint venture, trust or other enterprise, or (c) who was an
employee or agent of a corporation which was a predecessor corporation of the
corporation or of another enterprise at the request of such predecessor
corporation.

         6.3      PAYMENT OF EXPENSES IN ADVANCE.

                  Expenses incurred in defending any action or proceeding for
which indemnification is required pursuant to Section 6.1 or for which
indemnification is permitted pursuant to Section 6.2 following authorization
thereof by the Board of Directors shall be paid by the corporation in advance of
the final disposition of such action or proceeding upon receipt of an
undertaking by or on behalf of the indemnified party to repay such amount if it
shall ultimately


                                      -14-
<PAGE>


be determined that the indemnified party is not entitled to be indemnified as
authorized in this Article VI.

         6.4      INDEMNITY NOT EXCLUSIVE.

                  The indemnification provided by this Article VI shall not be
deemed exclusive of any other rights to which those seeking indemnification may
be entitled under any bylaw, agreement, vote of shareholders or disinterested
directors or otherwise, both as to action in an official capacity and as to
action in another capacity while holding such office, to the extent that such
additional rights to indemnification are authorized in the certificate of
incorporation.

         6.5      INSURANCE.

                  The corporation may purchase and maintain insurance on behalf
of any person who is or was a director, officer, employee or agent of the
corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise against any liability asserted against him or
her and incurred by him or her in any such capacity, or arising out of his or
her status as such, whether or not the corporation would have the power to
indemnify him or her against such liability under the provisions of the General
Corporation Law of Delaware.

         6.6      CONFLICTS.

                  No indemnification or advance shall be made under this Article
VI, except where such indemnification or advance is mandated by law or the
order, judgment or decree of any court of competent jurisdiction, in any
circumstance where it appears:

                  (a)      That it would be inconsistent with a provision of the
certificate of incorporation, these Bylaws, a resolution of the stockholders or
an agreement in effect at the time of the accrual of the alleged cause of the
action asserted in the proceeding in which the expenses were incurred or other
amounts were paid, which prohibits or otherwise limits indemnification; or

                  (b)      That it would be inconsistent with any condition
expressly imposed by a court in approving a settlement.

                                   ARTICLE VII

                               RECORDS AND REPORTS

         7.1      MAINTENANCE AND INSPECTION OF RECORDS.

                  The corporation shall, either at its principal executive
offices or at such place or places as designated by the Board of Directors, keep
a record of its stockholders listing their names and addresses and the number
and class of shares held by each stockholder, a copy of these Bylaws as amended
to date, accounting books, and other records.


                                      -15-
<PAGE>


                  Any stockholder of record, in person or by attorney or other
agent, shall, upon written demand under oath stating the purpose thereof, have
the right during the usual hours for business to inspect for any proper purpose
the corporation's stock ledger, a list of its stockholders, and its other books
and records and to make copies or extracts therefrom. A proper purpose shall
mean a purpose reasonably related to such person's interest as a stockholder. In
every instance where an attorney or other agent is the person who seeks the
right to inspection, the demand under oath shall be accompanied by a power of
attorney or such other writing that authorizes the attorney or other agent to so
act on behalf of the stockholder. The demand under oath shall be directed to the
corporation at its registered office in Delaware or at its principal place of
business.

         7.2      INSPECTION BY DIRECTORS.

                  Any director shall have the right to examine the corporation's
stock ledger, a list of its stockholders, and its other books and records for a
purpose reasonably related to his or her position as a director. The Court of
Chancery is hereby vested with the exclusive jurisdiction to determine whether a
director is entitled to the inspection sought. The Court may summarily order the
corporation to permit the director to inspect any and all books and records, the
stock ledger, and the stock list and to make copies or extracts therefrom. The
Court may, in its discretion, prescribe any limitations or conditions with
reference to the inspection, or award such other and further relief as the Court
may deem just and proper.

         7.3      ANNUAL STATEMENT TO STOCKHOLDERS.

                  The Board of Directors shall present at each annual meeting,
and at any special meeting of the stockholders when called for by vote of the
stockholders, a full and clear statement of the business and condition of the
corporation.

                                  ARTICLE VIII

                                 GENERAL MATTERS

         8.1      CHECKS.

                  From time to time, the Board of Directors shall determine by
resolution which person or persons may sign or endorse all checks, drafts, other
orders for payment of money, notes or other evidences of indebtedness that are
issued in the name of or payable to the corporation, and only the persons so
authorized shall sign or endorse those instruments.

         8.2      EXECUTION OF CORPORATE CONTRACTS AND INSTRUMENTS.

                  The Board of Directors, except as otherwise provided in these
Bylaws, may authorize any officer or officers, or agent or agents, to enter into
any contract or execute any instrument in the name of and on behalf of the
corporation; such authority may be general or confined to specific instances.
Unless so authorized or ratified by the Board of Directors or within the agency
power of an officer, no officer, agent or employee shall have any power or


                                      -16-
<PAGE>


authority to bind the corporation by any contract or engagement or to pledge its
credit or to render it liable for any purpose or for any amount.

         8.3      STOCK CERTIFICATES; PARTLY PAID SHARES.

                  The shares of a corporation shall be represented by
certificates, provided that the Board of Directors of the corporation may
provide by resolution or resolutions that some or all of any or all classes or
series of its stock shall be uncertificated shares. Any such resolution shall
not apply to shares represented by a certificate until such certificate is
surrendered to the corporation. Notwithstanding the adoption of such a
resolution by the Board of Directors, every holder of stock represented by
certificates and upon request every holder of uncertificated shares shall be
entitled to have a certificate signed by, or in the name of the corporation by
the chairman or vice-chairman of the Board of Directors, or the president or
vice-president, and by the chief financial officer or an assistant treasurer, or
the secretary or an assistant secretary of such corporation representing the
number of shares registered in certificate form. Any or all of the signatures on
the certificate may be a facsimile. In case any officer, transfer agent or
registrar who has signed or whose facsimile signature has been placed upon a
certificate has ceased to be such officer, transfer agent or registrar before
such certificate is issued, it may be issued by the corporation with the same
effect as if he or she were such officer, transfer agent or registrar at the
date of issue.

                  The corporation may issue the whole or any part of its shares
as partly paid and subject to call for the remainder of the consideration to be
paid therefor. Upon the face or back of each stock certificate issued to
represent any such partly paid shares, upon the books and records of the
corporation in the case of uncertificated partly paid shares, the total amount
of the consideration to be paid therefor and the amount paid thereon shall be
stated. Upon the declaration of any dividend on fully paid shares, the
corporation shall declare a dividend upon partly paid shares of the same class,
but only upon the basis of the percentage of the consideration actually paid
thereon.

         8.4      SPECIAL DESIGNATION ON CERTIFICATES.

                  If the corporation is authorized to issue more than one class
of stock or more than one series of any class, then the powers, the
designations, the preferences, and the relative, participating, optional or
other special rights of each class of stock or series thereof and the
qualifications, limitations or restrictions of such preferences and/or rights
shall be set forth in full or summarized on the face or back of the certificate
that the corporation shall issue to represent such class or series of stock;
provided, however, that, except as otherwise provided in Section 202 of the
General Corporation Law of Delaware, in lieu of the foregoing requirements there
may be set forth on the face or back of the certificate that the corporation
shall issue to represent such class or series of stock a statement that the
corporation will furnish without charge to each stockholder who so requests the
powers, the designations, the preferences, and the relative, participating,
optional or other special rights of each class of stock or series thereof and
the qualifications, limitations or restrictions of such preferences and/or
rights.


                                      -17-
<PAGE>


         8.5      LOST CERTIFICATES.

                  Except as provided in this Section 8.5, no new certificates
for shares shall be issued to replace a previously issued certificate unless the
latter is surrendered to the corporation and cancelled at the same time. The
corporation may issue a new certificate of stock or uncertificated shares in the
place of any certificate previously issued by it, alleged to have been lost,
stolen or destroyed, and the corporation may require the owner of the lost,
stolen or destroyed certificate, or the owner's legal representative, to give
the corporation a bond sufficient to indemnify it against any claim that may be
made against it on account of the alleged loss, theft or destruction of any such
certificate or the issuance of such new certificate or uncertificated shares.

         8.6      CONSTRUCTION; DEFINITIONS.

                  Unless the context requires otherwise, the general provisions,
rules of construction, and definitions in the Delaware General Corporation Law
shall govern the construction of these Bylaws. Without limiting the generality
of this provision, the singular number includes the plural, the plural number
includes the singular, and the term "person" includes both a corporation and a
natural person.

         8.7      DIVIDENDS.

                  The directors of the corporation, subject to any restrictions
contained in (a) the General Corporation Law of Delaware or (b) the certificate
of incorporation, may declare and pay dividends upon the shares of its capital
stock. Dividends may be paid in cash, in property, or in shares of the
corporation's capital stock.

                  The directors of the corporation may set apart out of any of
the funds of the corporation available for dividends a reserve or reserves for
any proper purpose and may abolish any such reserve. Such purposes shall include
but not be limited to equalizing dividends, repairing or maintaining any
property of the corporation, and meeting contingencies.

         8.8      FISCAL YEAR.

                  The fiscal year of the corporation shall be fixed by
resolution of the Board of Directors and may be changed by the Board of
Directors.

         8.9      SEAL.

                  The corporation may adopt a corporate seal, which may be
altered at pleasure, and may use the same by causing it or a facsimile thereof,
to be impressed or affixed or in any other manner reproduced.

         8.10     TRANSFER OF STOCK.

                  Upon surrender to the corporation or the transfer agent of the
corporation of a certificate for shares duly endorsed or accompanied by proper
evidence of succession,


                                      -18-
<PAGE>


assignation or authority to transfer, it shall be the duty of the corporation to
issue a new certificate to the person entitled thereto, cancel the old
certificate, and record the transaction in its books.

         8.11     STOCK TRANSFER AGREEMENTS.

                  The corporation shall have power to enter into and perform any
agreement with any number of stockholders of any one or more classes of stock of
the corporation to restrict the transfer of shares of stock of the corporation
of any one or more classes owned by such stockholders in any manner not
prohibited by the General Corporation Law of Delaware.

         8.12     REGISTERED STOCKHOLDERS.

                  The corporation shall be entitled to recognize the exclusive
right of a person registered on its books as the owner of shares to receive
dividends and to vote as such owner, shall be entitled to hold liable for calls
and assessments the person registered on its books as the owner of shares, and
shall not be bound to recognize any equitable or other claim to or interest in
such share or shares on the part of another person, whether or not it shall have
express or other notice thereof, except as otherwise provided by the laws of
Delaware.

                                   ARTICLE IX

                                   AMENDMENTS

                  The Bylaws of the corporation may be adopted, amended or
repealed by the stockholders entitled to vote; provided, however, that the
corporation may, in its certificate of incorporation, confer the power to adopt,
amend or repeal Bylaws upon the directors. The fact that such power has been so
conferred upon the directors shall not divest the stockholders of the power, nor
limit their power to adopt, amend or repeal Bylaws.



                                      -19-
<PAGE>


                           CERTIFICATE OF ADOPTION OF

                           AMENDED AND RESTATED BYLAWS

                                       OF

                           ROSETTA INPHARMATICS, INC.

         The undersigned hereby certifies that he is the duly elected,
qualified, and acting Secretary of Rosetta Inpharmatics, Inc. (the
"CORPORATION") and that the foregoing Bylaws, comprising 22 pages, were
adopted as the Bylaws of the Corporation effective on March 26, 2001, by the
Board of Directors of the Corporation.

         IN WITNESS WHEREOF, the undersigned has executed this Certificate of
Adoption on March 26, 2001.



----------------------------------
John J. King, II
Secretary