CHIRON CORP
DEF 14A, 1995-04-18
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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<PAGE>
                            SCHEDULE 14A INFORMATION

                  Proxy Statement Pursuant to Section 14(a) of
            the Securities Exchange Act of 1934 (Amendment No.    )

    Filed by the Registrant /X/
    Filed by a Party other than the Registrant / /

    Check the appropriate box:
    / /  Preliminary Proxy Statement
    / /  Confidential, for Use of the Commission Only (as permitted by Rule
         14a-6(e)(2))
    /X/  Definitive Proxy Statement
    / /  Definitive Additional Materials
    / /  Soliciting  Material  Pursuant  to  Section  240.14a-11(c)  or  Section
         240.14a-12

                                CHIRON CORPORATION
- - --------------------------------------------------------------------------------
                (Name of Registrant as Specified In Its Charter)

- - --------------------------------------------------------------------------------
    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

/X/  $125 per  Exchange Act  Rules 0-11(c)(1)(ii),  14a-6(i)(1), 14a-6(i)(2)  or
     Item 22(a)(2) of Schedule 14A.
/ /  $500  per  each party  to  the controversy  pursuant  to Exchange  Act Rule
     14a-6(i)(3).
/ /  Fee  computed  on   table  below   per  Exchange   Act  Rules   14a-6(i)(4)
     and 0-11.
     1) Title of each class of securities to which transaction applies:
        ------------------------------------------------------------------------
     2) Aggregate number of securities to which transaction applies:
        ------------------------------------------------------------------------
     3) Per unit price or other underlying value of transaction computed
        pursuant to Exchange Act Rule 0-11 (Set forth the amount on which the
        filing fee is calculated and state how it was determined):
        ------------------------------------------------------------------------
     4) Proposed maximum aggregate value of transaction:
        ------------------------------------------------------------------------
     5) Total fee paid:
        ------------------------------------------------------------------------
/ /  Fee paid previously with preliminary materials.
/ /  Check box if any part of the fee is offset as provided by Exchange Act Rule
     0-11(a)(2)  and identify the  filing for which the  offsetting fee was paid
     previously. Identify the previous filing by registration statement  number,
     or the Form or Schedule and the date of its filing.
     1) Amount Previously Paid:
        ------------------------------------------------------------------------
     2) Form, Schedule or Registration Statement No.:
        ------------------------------------------------------------------------
     3) Filing Party:
        ------------------------------------------------------------------------
     4) Date Filed:
        ------------------------------------------------------------------------
<PAGE>
[LOGO]                                                            April 18, 1995

To the Stockholders of
CHIRON CORPORATION

    You  are cordially invited  to attend the Annual  Meeting of Stockholders of
Chiron Corporation ("Chiron" or the "Company")  on May 18, 1995, at 10:00  a.m.,
which will be held at 1450 - 53rd Street, Emeryville, California 94608.

    The  attached  Notice  of Annual  Meeting  and Proxy  Statement  explain the
business to be conducted at the Annual Meeting.

    Also included in  this package is  Chiron's 1994 Annual  Report. The  Annual
Report  is in  summary form, containing  selected financial data,  our letter to
stockholders, and highlights of operations. You will find the Company's  audited
consolidated financial statements enclosed as a separate brochure in a pocket at
the back of the Annual Report.

    Whether or not you plan to attend the Annual Meeting, please sign, date, and
return  the enclosed proxy  promptly in the accompanying  reply envelope. If you
decide to attend the Annual Meeting and wish to change your proxy vote, you  may
do so by giving notice and voting in person at the Annual Meeting.

    We look forward to seeing you at the Annual Meeting.

                                          EDWARD E. PENHOET

                                          EDWARD E. PENHOET,
                                            PRESIDENT AND
                                           CHIEF EXECUTIVE OFFICER
<PAGE>
                               CHIRON CORPORATION
                               4560 HORTON STREET
                          EMERYVILLE, CALIFORNIA 94608

                    NOTICE OF ANNUAL MEETING OF STOCKHOLDERS
                          MAY 18, 1995, AT 10:00 A.M.

    You  are hereby notified  that the Annual Meeting  of Stockholders of Chiron
Corporation ("Chiron" or  the "Company")  will be held  at 1450  - 53rd  Street,
Emeryville,  California,  on Thursday,  May  18, 1995,  at  10:00 a.m.,  for the
following purposes:

        1.  To elect four Class II directors to hold office for three years;

        2.   To consider  and vote  upon  a proposal  to approve  the  Company's
    amended 1991 Stock Option Plan;

        3.  To consider and vote upon a proposal to adopt the Chiron Corporation
    1995 Executive Officer Variable Cash Compensation Plan;

        4.   To  ratify the  selection of KPMG  Peat Marwick  LLP as independent
    public accountants for the current fiscal year; and

        5.  To transact  such other business that  may properly come before  the
    Annual Meeting or any adjournments or postponements thereof.

    Stockholders  of record at the close of  business on March 31, 1995, will be
entitled to vote at the Annual Meeting.  A list of the stockholders entitled  to
vote  at the Annual Meeting will be  open to the examination of any stockholder,
for any purpose  germane to the  meeting, during ordinary  business hours for  a
period of ten days prior to the meeting at the principal executive office of the
Company at 4560 Horton Street, Emeryville, California 94608.

    WHETHER OR NOT YOU PLAN TO ATTEND THE ANNUAL MEETING, PLEASE SIGN, DATE, AND
RETURN  THE ENCLOSED PROXY IN THE REPLY  ENVELOPE PROVIDED. The prompt return of
your proxy will assist us in preparing for the Annual Meeting.

                                          BY ORDER OF THE BOARD OF DIRECTORS

                                          WILLIAM G. GREEN
                                          WILLIAM G. GREEN,
                                            SECRETARY

Emeryville, California
April 18, 1995
<PAGE>
                                PROXY STATEMENT
                                      FOR
                         ANNUAL MEETING OF STOCKHOLDERS
                            TO BE HELD MAY 18, 1995

    These  proxy materials are furnished in  connection with the solicitation of
proxies by the Board of Directors of CHIRON CORPORATION, a Delaware  corporation
("Chiron"  or the "Company"),  for the Annual Meeting  of Stockholders of Chiron
(the "Annual Meeting"), to be held at 1450 - 53rd Street, Emeryville, California
94608 at 10:00 a.m. on May 18, 1995, and at any adjournments or postponements of
the Annual Meeting. These proxy materials  were first mailed to stockholders  on
or about April 18, 1995.

                               PURPOSE OF MEETING

    The specific proposals to be considered and acted upon at the Annual Meeting
are  summarized in  the accompanying Notice  of Annual  Meeting of Stockholders.
Each of these proposals  is described in more  detail in subsequent sections  of
this Proxy Statement.

                         VOTING RIGHTS AND SOLICITATION

    The Company has one type of security entitled to vote at the Annual Meeting,
its  Common Stock (the "Common  Stock"). If you were  a stockholder of record of
Common Stock at the  close of business on  March 31, 1995, you  may vote at  the
Annual  Meeting. Each  share entitles  you to  one vote  on each  matter to come
before the Annual Meeting.  On March 31, 1995,  there were 40,045,138 shares  of
Common  Stock issued  and outstanding. The  Certificate of  Incorporation of the
Company does not  provide for cumulative  voting. If you  were a stockholder  of
record  of Cetus Corporation common stock at  the close of business on March 31,
1995, and have not  exchanged your Cetus common  stock for Chiron Common  Stock,
you  nevertheless may  vote at  the Annual Meeting.  Each share  of Cetus common
stock entitles you to 0.3 of one vote  on each matter to come before the  Annual
Meeting.

    If  you are unable to attend the Annual  Meeting, you may vote by proxy. The
enclosed proxy is solicited by the Chiron Board of Directors and, when the proxy
card is returned  properly completed, it  will be  voted as you  direct on  your
proxy card. You are urged to specify your choices on the enclosed proxy card. If
a proxy card is signed and returned without choices specified, in the absence of
contrary instructions, the shares of Common Stock represented by such proxy will
be  voted "FOR" Proposals 1, 2, 3 and 4  and will be voted in the proxy holders'
discretion as to other matters that may properly come before the Annual Meeting.

    You may revoke or change  your proxy at any time  before it is exercised  at
the  Annual Meeting. To do this, send  a written notice of revocation or another
signed proxy with a later date than appears  on the proxy you wish to revoke  to
the  Secretary of Chiron, William G. Green, at the Company's principal executive
office. You also may revoke your proxy by giving notice and voting in person  at
the Annual Meeting.

    The  Company will  pay the cost  of soliciting these  proxies, including the
printing, handling, and  mailing of the  proxies and related  material, and  the
actual   expenses  incurred  by  brokerage  houses,  custodians,  nominees,  and
fiduciaries in forwarding proxy material to  the beneficial owners of stock.  To
assure  that holders of a majority of the  stock will be present in person or by
proxy at the Annual Meeting, certain officers, directors, and regular  employees
of  Chiron may solicit proxies by  telephone, telegraph, facsimile or in person.
These persons will receive no extra compensation for their services.

                               VOTING PROCEDURES

    The four nominees for  election as directors at  the 1995 Annual Meeting  of
Stockholders  who receive the greatest number of  votes cast for the election of
directors at that meeting by the holders of the Company's Common Stock, entitled
to vote at that meeting, a quorum  being present, shall become directors at  the
conclusion of the tabulation of votes.

                                       1
<PAGE>
    The affirmative vote of the majority of shares of Common Stock having voting
power  present  in person  or  represented by  proxy  at the  Annual  Meeting is
required to adopt the proposals relating to approval of the amended Chiron  1991
Stock  Option Plan and adoption of the Chiron Corporation 1995 Executive Officer
Variable Cash Compensation Plan.

    The Inspector  of  Elections will  treat  an abstention  or  withholding  of
authority  to vote  on the  election of  directors by  a stockholder  present in
person or represented by proxy at the meeting as unvoted for such purposes.  The
Inspector  of Elections will treat an abstention  as to the proposal relating to
approval of the amended Chiron 1991  Stock Option Plan or the proposal  relating
to  adoption  of the  Chiron Corporation  1995  Executive Officer  Variable Cash
Compensation Plan by a stockholder present in person or represented by proxy  at
the  meeting as a vote "against" the matter for such purposes. However, pursuant
to Delaware law and  the Company's Bylaws, broker  non-votes as to the  proposal
relating  to  approval of  the  amended Chiron  1991  Stock Option  Plan  or the
proposal relating to adoption of  the Chiron Corporation 1995 Executive  Officer
Variable  Cash  Compensation Plan  are  treated as  shares  of Common  Stock not
present, or represented, and not entitled to vote on such proposals, will not be
counted as votes  for or against  and will  not be included  in calculating  the
number of votes necessary for approval of such proposals.

                             CIBA-GEIGY TRANSACTION

    Effective January 1, 1995, Ciba-Geigy Limited ("Ciba"), a Swiss corporation,
and  the Company  closed a transaction  (the "Closing")  previously announced on
November 21,  1994  to  form  a strategic  partnership.  Chiron  and  Ciba  will
collaborate to discover, develop, manufacture and market biotechnology and other
healthcare  products as  the parties  may agree  from time  to time  on a global
scale. Under  the terms  of the  agreement, Chiron  and Ciba  will be  preferred
partners  seeking to leverage  the complementary strengths  of the two companies
through cooperative  approaches,  but each  will  remain independent  to  pursue
projects  outside of the partnership. As part of the transaction, Ciba purchased
through a partial tender  offer 11,860,467 shares  of the Company's  outstanding
Common  Stock  from  the stockholders  at  $117  per share.  Ciba  also acquired
6,600,000 new shares of Common  Stock issued by Chiron  in exchange for all  the
outstanding  stock of Ciba Corning Diagnostics Corp. and Ciba's interests in The
Biocine Company and  JV Vax B.V.  These newly acquired  shares of Common  Stock,
when  combined with the  approximately 1,367,372 shares  that Ciba already held,
result in Ciba owning approximately 49.5 percent of the outstanding Common Stock
of the Company.

    On November  20,  1994, Chiron  and  Ciba  entered into  an  agreement  (the
"Governance   Agreement")  which  contains  terms   relating  to  the  corporate
governance of  the  Company  following  the  Closing  and  the  acquisition  and
disposition  of  securities of  the Company  by Ciba  and its  subsidiaries. The
Governance Agreement provides  that, from and  after the Closing,  the Board  of
Directors of the Company will be comprised of 11 directors (each, a "Director"),
and  the  number of  directors may  be  increased only  as described  below. The
Nominating Committee of the Board of Directors (the "Nominating Committee") will
nominate persons to  serve as Directors  as described below  and each person  so
nominated  will be  included in management's  slate of nominees  for each annual
meeting of the  stockholders of  the Company. The  Governance Agreement  further
provides  that the Nominating Committee will  nominate three persons to serve as
management Directors (each a "Management Director"), two of whom will be the two
most senior executives of the Company and the third of whom will be an  employee
of the Company (or a person otherwise designated as a Management Director by the
Nominating  Committee). In addition, Ciba will have the right to designate three
persons to serve as Directors (each, an "Investor Director"), any of whom may be
officers or employees of Ciba or its affiliates. If, however, Ciba's  Percentage
Interest  (as defined below) for any period is less than 30 percent but at least
20 percent, during that period Ciba will instead have the right to designate for
nomination only two Investor  Directors, and, if  Ciba's Percentage Interest  is
less  than 20 percent for any period,  during that period Ciba will instead have
the right  to designate  for  nomination only  one  Investor Director.  As  used
herein,  "Ciba's  Percentage Interest"  means  the percentage  of  voting power,
determined on  the  basis of  the  number of  shares  of voting  stock  actually
outstanding, that is controlled directly or indirectly by Ciba or any subsidiary
of  Ciba (other than  the Company and its  subsidiaries) including by beneficial
ownership.   Finally,    the   Nominating    Committee   will    nominate    the

                                       2
<PAGE>
remaining  Directors (the  "Independent Directors"), each  of whom  must have an
outstanding reputation for personal  integrity and distinguished achievement  in
areas  relevant to the Company and, under the terms of the Governance Agreement,
must meet certain  criteria demonstrating such  person's independence from  both
Ciba  and the Company. Pursuant to the Governance Agreement, on January 4, 1995,
the Board of  Directors elected  three nominees of  Ciba: Dr.  Alex Krauer,  Mr.
Pierre  Douaze  and  Dr.  Francois  L'Eplattenier,  to  serve  on  the  Board as
representatives of Ciba.

    Under the  terms  of the  Governance  Agreement,  Ciba agreed  that  in  any
election  of  directors or  any meeting  of stockholders  of the  Company called
expressly for  the removal  of directors,  so  long as  the Board  of  Directors
includes  (and  will include  after  any such  removal)  the number  of Investor
Directors contemplated by the Governance Agreement, Ciba and its affiliates will
be present for purposes of establishing a quorum and will vote all their  shares
of  voting stock (i) in favor of any  nominee or director selected or removed in
accordance with the terms of the Governance Agreement, (ii) in favor of  removal
of  any Director in circumstances where the number of Investor Directors is more
than required under the terms of that Agreement and (iii) otherwise against  the
removal  of any director designated in accordance with the Governance Agreement.
In any other matter submitted to a vote of the stockholders of the Company, Ciba
may vote any or all of its shares in its sole discretion unless such matter  was
approved  by Ciba or a majority of the Investor Directors in accordance with the
terms of the Governance  Agreement, in which case  Ciba and its affiliates  will
cast all their votes in favor of such matter. Because a majority of the Investor
Directors  have approved the amended 1991 Stock  Option Plan and the adoption of
the Chiron Corporation  1995 Executive Officer  Variable Cash Compensation  Plan
which are the subjects of Proposals 2 and 3 of this Proxy Statement, the Company
anticipates that Ciba will cast all of its votes in favor of such matters at the
Annual Meeting.

    STANDSTILL.   Under the terms of the Governance Agreement, during the period
beginning at  the  Closing and  terminating  at  January 15,  2000  (the  "First
Standstill  Period"), Ciba has agreed that  it will not, directly or indirectly,
purchase or otherwise acquire any Equity Securities (as defined below) from  any
person  other than the Company unless (i)  such acquisition is a Market Purchase
(as defined  below) and  (ii) immediately  after such  purchase or  acquisition,
Ciba's  Percentage Interest would  not exceed the greatest  of (A) 49.9 percent,
(B) the highest  Ciba's Percentage  Interest resulting from  any acquisition  by
Ciba or its affiliates of Equity Securities that has been approved by a majority
of  the  Independent Directors  as described  below and  (C) the  highest Ciba's
Percentage Interest immediately following any action by the Company (including a
purchase by the  Company of outstanding  Equity Securities or  a sale of  Equity
Securities  to  Ciba or  its affiliates  by the  Company) that  increases Ciba's
Percentage Interest.

    As defined in the  Governance Agreement, "Equity  Securities" means (i)  the
Common  Stock and any other voting stock  of the Company, (ii) any securities of
the Company convertible into  or exchangeable for Common  Stock or other  voting
stock  or  (iii) any  options, rights  or warrants  (or any  similar securities)
issued by the Company to acquire Common Stock or other voting stock, and "Market
Purchase"  means  an  acquisition  of  Equity  Securities  that  is  within  the
definition  of "Rule  10b-18 Purchase"  under Rule  10b-18 under  the Securities
Exchange Act of 1934 (the "Exchange Act") as in effect on November 20, 1994 that
satisfies the conditions of paragraph (b) of Rule 10b-18.

    During the period beginning  at the end of  the First Standstill Period  and
terminating  at  the date  that Ciba  and its  affiliates become  the beneficial
owners of all outstanding shares of  Equity Securities, Ciba has further  agreed
that  it will  not, directly  or indirectly,  purchase or  otherwise acquire any
Equity Securities  from  any person  other  than  the Company  unless  (i)  such
acquisition  is a  Market Purchase and  (ii) immediately after  such purchase or
acquisition, Ciba's Percentage Interest would not exceed the greatest of (A)  55
percent,   (B)  the  highest  Ciba's  Percentage  Interest  resulting  from  any
acquisition by  Ciba  or its  affiliates  of  Equity Securities  that  has  been
approved  by a majority of the Independent  Directors as described below and (C)
the highest Ciba's Percentage Interest  immediately following any action by  the
Company (including a purchase by the Company of outstanding Equity Securities or
a  sale of  Equity Securities  to Ciba  or its  affiliates by  the Company) that
increases Ciba's Percentage Interest.

                                       3
<PAGE>
    Except with  respect  to  a  Buyout  Transaction  (as  defined  below),  the
Governance  Agreement provides that any other  purchase or acquisition of Equity
Securities by Ciba or its affiliates from any person other than the Company will
require the approval of a majority of the Independent Directors acting solely in
the interest of the unaffiliated stockholders and in granting such approval  the
Independent  Directors, unless a majority of them decide otherwise, will require
a purchase price for such Equity Securities reflecting a proportionate share  of
then  prevailing Third Party Sale Value (as  defined below), except that no such
purchase may increase Ciba's Percentage Interest above 79.9 percent.

    As defined in the Governance Agreement,  "Third Party Sale Value" means  the
value  that an  unaffiliated third party  would be expected  (based on financial
analyses generally used by investment bankers  in the preparation of a  fairness
opinion  for an acquisition transaction) to pay for all the Equity Securities of
the Company in an arm's-length transaction negotiated by a willing seller and  a
willing buyer.

    BUYOUT TRANSACTION.  The Governance Agreement provides that, notwithstanding
the  standstill  provisions  described  above,  at  any  time  after  the  sixth
anniversary of the Closing, but as early as the fifth anniversary of the Closing
if certain conditions  exist, Ciba may  propose and consummate  a tender  offer,
merger, sale of substantially all of the Company's assets or similar transaction
involving  Ciba or  one of  its affiliates and  the Company  or the unaffiliated
stockholders that (1)  offers each unaffiliated  stockholder the opportunity  to
dispose of all Equity Securities owned by such stockholder or otherwise provides
for  the acquisition of all Equity Securities owned by such stockholder, in each
case for  consideration reflecting  such  stockholder's proportionate  share  of
consideration  at least equal to  Third Party Sale Value  (the "Third Party Sale
Value Consideration") and (2) for each class of Equity Securities, provides  the
same  consideration for  each security within  such class  (any such transaction
being referred to  herein as  a "Buyout Transaction").  Under the  terms of  the
Governance  Agreement, a Buyout Transaction may  only be consummated pursuant to
certain procedures specified therein.

    The Governance  Agreement  provides  that  until  Ciba  and  its  affiliates
beneficially  own  all outstanding  shares of  Equity  Securities, Ciba  and its
subsidiaries will  not  (i)  make,  or  in  any  way  participate,  directly  or
indirectly,  in any "solicitation" of "proxies" to  vote (as such terms are used
in the proxy rules of the Securities and Exchange Commission) or seek to advise,
encourage or influence any person  or entity with respect  to the voting of  any
shares  of capital stock of the  Company, initiate, propose or otherwise solicit
stockholders of  the  Company  for  the approval  of  one  or  more  stockholder
proposals   or  induce  or  attempt  to   induce  any  other  individual,  firm,
corporation, partnership or other entity  to initiate any stockholder  proposal;
or  (ii) deposit any shares  of voting stock into a  voting trust or subject any
shares of  voting stock  to any  arrangement or  agreement with  respect to  the
voting  of  such  securities or  form,  join or  in  any way  participate  in or
otherwise encourage  the formation  of, with  respect to  any shares  of  Common
Stock, any group of persons formed for the purpose of acquiring, holding, voting
or  disposing of voting stock which would be required under Section 13(d) of the
Exchange Act, and the rules and  regulations thereunder, to file a statement  on
Schedule  13D with the  Securities and Exchange Commission  as a "person" within
the meaning of Section 13(d)(3) of  the Exchange Act if such group  beneficially
owned voting stock representing more than 5 percent of any class of voting stock
then outstanding.

                                       4
<PAGE>
                             PRINCIPAL STOCKHOLDERS

    The  following is the only person known by Chiron to own beneficially, as of
March 31, 1995, 5 percent or more of the outstanding shares of its Common Stock.

    On March  31, 1995,  there were  40,045,138 shares  of Chiron  Common  Stock
outstanding.

<TABLE>
<CAPTION>
                                                                                  AMOUNT AND
                                                                                  NATURE OF
                                                                                  BENEFICIAL     PERCENT
NAME AND ADDRESS OF BENEFICIAL OWNER                                             OWNERSHIP(1)   OF CLASS
- - -------------------------------------------------------------------------------  ------------  -----------
<S>                                                                              <C>           <C>
Ciba-Geigy Limited ............................................................   19,827,839        49.5%
 Klybeckstrasse CH-4002
 Basel, Switzerland
<FN>
- - ------------------------

(1)  Under  the terms of the Governance  Agreement, Ciba is permitted to acquire
     up to 49.9 percent of the  Company's Common Stock through market  purchases
     and  to participate pro rata in certain  issuances of new securities by the
     Company. In addition,  in certain instances,  under the terms  of a  Market
     Price  Option Agreement between Ciba and  the Company, Ciba is permitted to
     purchase Common Stock directly  from the Company  upon the satisfaction  of
     certain   conditions.  See  "Related  Transactions"  below  for  a  further
     discussion of Chiron's relationships with Ciba.
</TABLE>

                        SECURITY OWNERSHIP OF MANAGEMENT

    The following table sets forth the  beneficial ownership of Common Stock  of
Chiron  as of  March 31,  1995, by  each director  and nominee  to the  Board of
Directors,  the  Chief  Executive  Officer  and  the  four  other  most   highly
compensated  executive  officers and,  as  a group,  by  such persons  and other
executive officers of Chiron. All shares are subject to the named person's  sole
voting and investment power.

<TABLE>
<CAPTION>
                                                                                AMOUNT AND
                                                                                 NATURE OF
                                                                                BENEFICIAL      PERCENT
NAME OF BENEFICIAL OWNER                                                       OWNERSHIP (1)  OF CLASS (2)
- - -----------------------------------------------------------------------------  -------------  ------------
<S>                                                                            <C>            <C>
Gilbert F. Amelio............................................................        10,624        *
Lewis W. Coleman.............................................................        12,617        *
Pierre Douaze................................................................         1,250        *
Donald A. Glaser.............................................................       102,338        *
William G. Green.............................................................        93,870        *
Alex Krauer..................................................................         1,250        *
Francois L'Eplattenier.......................................................         1,250        *
David W. Martin..............................................................        10,000        *
Edward E. Penhoet............................................................       250,819        *
William J. Rutter............................................................       640,851       1.6 %
Henri Schramek...............................................................        18,000        *
Jack W. Schuler..............................................................        34,970        *
Pieter J. Strijkert..........................................................        17,400        *
Dennis L. Winger.............................................................       102,306        *
All directors and executive officers as a group (28 persons).................     1,793,367       4.5 %

                                                                                   (FOOTNOTES ON FOLLOWING
                                                                                                     PAGE)
</TABLE>

                                       5
<PAGE>
<TABLE>
<S>                                                                            <C>            <C>
<FN>
- - ------------------------
(1)  This   disclosure  is  made  pursuant  to  certain  rules  and  regulations
     promulgated by  the  Securities and  Exchange  Commission, and  in  certain
     instances,  the number of shares shown  as being beneficially owned may not
     be deemed  to be  beneficially owned  for other  purposes. Includes  shares
     which  are subject to options or warrants  exercisable on or before May 30,
     1995, in the  following amounts:  Dr. Amelio, 10,500  shares; Mr.  Coleman,
     12,000  shares; Mr.  Douaze, 1,250 shares;  Dr. Glaser,  37,650 shares; Mr.
     Green, 93,228 shares;  Dr. Krauer, 1,250  shares; Dr. L'Eplattenier,  1,250
     shares;  Dr. Martin, 10,000 shares; Dr.Penhoet, 171,209 shares; Dr. Rutter,
     226,209 shares; Dr.  Schramek, 18,000 shares;  Mr. Schuler, 34,167  shares;
     Dr. Strijkert, 17,400 shares; Mr. Winger, 100,075 shares; and all directors
     and executive officers as a group, 1,142,954 shares.

(2)  Percentage  of outstanding  Common Stock  and of  Common Stock  that may be
     acquired upon exercise of outstanding options and warrants on or before May
     30, 1995, by  the persons named  above and by  all directors and  executive
     officers   as  a  group.  The  asterisk   (*)  indicates  that  the  shares
     beneficially  owned  represent  less  than   one  percent  of  the   shares
     outstanding.
</TABLE>

                                  PROPOSAL 1:
                             ELECTION OF DIRECTORS

    Chiron  has three classes  of directors serving  staggered three-year terms.
Three directors presently serve in Class I, four directors in Class II and  four
directors  in  Class  III. This  year,  the following  four  directors presently
serving in Class II are nominated to be reelected for three-year terms  expiring
in  1998: Drs. Gilbert F.  Amelio, Edward E. Penhoet  and Henri Schramek and Mr.
Pierre Douaze.  See "Ciba-Geigy  Transaction" at  pp. 2-4  for a  discussion  of
matters relating to Ciba's voting of shares held by it and its affiliates in any
election of directors.

           THE BOARD OF DIRECTORS RECOMMENDS A VOTE FOR EACH NOMINEE.

    The  persons named on the enclosed proxy (the "proxy holders") will vote for
election of the above-named nominees unless you have withheld authority for them
to do so on your proxy card. In the unanticipated event that a nominee is unable
to or declines to  serve as a director  at the time of  the Annual Meeting,  the
proxies will be voted for any nominee named by the present Board of Directors to
fill the vacancy. As of the date of this Proxy Statement, the Board of Directors
is  not aware of any nominee who is unable  to or who will decline to serve as a
director. In the  event that additional  persons are nominated  for election  as
directors, the proxy holders intend to vote all proxies received by them for the
nominees listed above.

                                       6
<PAGE>
    Information  as to the  nominees, and as  to each other  director whose term
will continue after the 1995 Annual Meeting of Stockholders, is given below.

<TABLE>
<CAPTION>
                                                                                                              SERVED AS
                    NAME                           AGE                  PRINCIPAL OCCUPATION               DIRECTOR SINCE
- - ---------------------------------------------      ---      ---------------------------------------------  ---------------
<S>                                            <C>          <C>                                            <C>
CLASS II (1998 CLASS)
  Gilbert F. Amelio..........................          52   President and Chief Executive Officer,                 1991
                                                             National Semiconductor Corporation
  Pierre Douaze..............................          55   Member of the Executive Committee of                   1995
                                                             management, Ciba-Geigy Limited
  Edward E. Penhoet..........................          54   President and Chief Executive Officer, Chiron          1981
                                                             Corporation
  Henri Schramek.............................          76   Retired; Former Member of the Board of                 1989
                                                             Directors, Ciba-Geigy Limited

CLASS III (1996 CLASS)
  Lewis W. Coleman...........................          53   Chief Financial Officer,                               1991
                                                             BankAmerica Corp.
  Francois L'Eplattenier.....................          56   Member of the Executive Committee of                   1995
                                                             management, Ciba-Geigy Limited
  William J. Rutter..........................          66   Chairman, Chiron Corporation                           1981
  Jack W. Schuler............................          54   Chairman, Stericycle Corporation                       1991

CLASS I (1997 CLASS)
  Donald A. Glaser...........................          68   Professor of Physics, of Molecular Biology,            1991
                                                             and of Neuroscience, University of
                                                             California, Berkeley
  Alex Krauer................................          64   Chairman of the Board and Chief Executive              1995
                                                             Officer, Ciba-Geigy Limited
  Pieter J. Strijkert........................          59   Advisor, Board of Management,                          1987
                                                             Gist-brocades Holding
</TABLE>

CLASS II (1998 CLASS)

    GILBERT F. AMELIO has been President, Chief Executive Officer and member  of
the  Board of Directors of National Semiconductor Corporation since joining that
company in  1991.  From  1988  until  joining  National  Semiconductor,  he  was
President  of the Communications System Group at Rockwell International, and was
President of  Rockwell's  Semiconductor Products  Division  from 1983  to  1988.
Previously,   he  held   management  and   research  positions   with  Fairchild
Semiconductor Corporation and AT&T's Bell  Laboratories. Dr. Amelio is a  member
of  the Boards of Directors of  the Semiconductor Industry Association, Sematech
and Apple Computer.

    PIERRE DOUAZE has been a member of the Executive Committee of management  of
Ciba-Geigy  Limited since  1991 and  Head of the  Pharma Division  of Ciba since
1989.

    EDWARD E. PENHOET, a cofounder of the Company and a director since 1981, has
served as Chief Executive Officer since the Company's inception. Dr. Penhoet has
been a  faculty member  of  the Biochemistry  Department  at the  University  of
California, Berkeley, for 23 years. Since 1983, he has been an Adjunct Professor
at that university.

    HENRI  SCHRAMEK became a director of the  Company in April 1989. He was with
Ciba-Geigy Limited for  thirty-eight years,  having retired  from operations  in
1983  and having served  as a Member of  the Board of  Directors of that company
from 1983 to 1988 and as Vice Chairman of the Board of Directors from 1987 until
1988.

                                       7
<PAGE>
CLASS III (1996 CLASS)

    LEWIS W. COLEMAN is Vice  Chairman of the Board  of Directors and the  Chief
Financial  Officer of  BankAmerica Corp. Mr.  Coleman joined Bank  of America in
1986 as Executive Vice President and Chief Credit Officer, World Banking  Group.
He  also has headed the Capital Markets Group and later served from 1990 to 1993
as Vice Chairman of  the Board and Head  of the World Banking  Group at Bank  of
America.  Mr. Coleman served with Bank of  California from 1963 to 1973 and with
Wells Fargo Bank from 1973 to 1986, in various positions.

    FRANCOIS L'EPLATTENIER  has been  a  Member of  the Executive  Committee  of
management of Ciba-Geigy Limited since 1988.

    WILLIAM  J.  RUTTER is  a cofounder  of the  Company and  has served  as its
Chairman of the Board since the Company's inception. In 1969, Dr. Rutter  joined
the  faculty  of  the  University  of  California,  San  Francisco  ("UCSF"), as
Hertzstein  Professor,  and  he  served   as  Chairman  of  the  Department   of
Biochemistry  and Biophysics at UCSF from 1969 to 1982. From August 1983 through
April 1989, in addition  to his responsibilities at  Chiron, Dr. Rutter was  the
Director  of the  Hormone Research  Institute at UCSF.  In May  1989, Dr. Rutter
became a full-time employee of Chiron and consequently vacated the  Directorship
of the Hormone Research Institute. He became Professor emeritus in 1991.

    JACK  W.  SCHULER  is Chairman  of  Stericycle Corporation,  a  company that
processes, sterilizes and recycles medical  waste. Prior to joining  Stericycle,
Mr.  Schuler was  President and Chief  Operating Officer  of Abbott Laboratories
("Abbott") from 1987 to 1989. He joined Abbott in 1972 as Director of Sales  and
Marketing  for the diagnostics  division, and held a  series of diagnostic sales
and management positions. He served on  the Abbott Board of Directors from  1985
to  1989. Mr. Schuler  is a member of  the Boards of  Directors of Somatogen and
Medtronic, Inc.

CLASS I (1997 CLASS)

    DONALD A. GLASER was a founder  of Cetus Corporation ("Cetus"), a member  of
its  Board  of  Directors  from 1971  to  1991,  and Chairman  of  the  Board of
Scientific Advisors of Cetus. He has served on the faculty at the University  of
California,  Berkeley, since 1959. Dr. Glaser  received a Nobel Prize in Physics
in 1960.

    ALEX KRAUER has been the Chairman  of the Board and Chief Executive  Officer
of Ciba-Geigy Limited since 1987.

    PIETER  J. STRIJKERT was  a member of the  Management Board of Gist-brocades
N.V.,  a   fermentation  and   pharmaceutical  company   headquartered  in   the
Netherlands,  from 1985 until 1993, and was Chairman of the Supervisory Board of
International Bio-Synthetics BV, now called Bio-Specialties Division, originally
a joint venture and now a division of Gist-brocades N.V., which is active in the
areas of industrial enzymes, bio-fine chemicals, biopolymers, and biopesticides,
from 1987  until 1991.  He is  now  an advisor  to the  board of  management  of
Gist-brocades Holding.

                           COMPENSATION OF DIRECTORS

    The  Company pays  each nonemployee director  a retainer fee  of $16,000 per
year; an additional fee  of $2,000 for  each meeting of  the Board of  Directors
attended  in person; an additional fee of $500 for each telephone meeting of the
Board of Directors; and a fee of $200 per hour, to a maximum of $1,000 per  day,
for  time spent on meetings of Committees of the Board of Directors on days when
no meeting  of the  Board  of Directors  is held.  The  Company also  pays  each
nonemployee  director  serving as  chairman of  one of  the Board  Committees an
additional retainer of $5,000 per year.

    Under the  Company's  1991  Stock  Option  Plan  (the  "Option  Plan"),  the
automatic  option  grant program  provides that  each nonemployee  director will
automatically be granted a non-statutory stock option ("Automatic Option Grant")
to purchase 3,000 shares of  the Company's Common Stock on  the last day of  the
second  quarter of each fiscal year, with an option price per share equal to the
fair market value (as defined  in the plan) of the  Common Stock on that  annual
grant date. The option exercise price is payable in cash, or in shares of Chiron
Common  Stock held for at least  six months, or with the  proceeds of a same day

                                       8
<PAGE>
sale of the option shares.  Each person who is newly  elected or appointed as  a
nonemployee  member of the  Board of Directors  after the effective  date of the
Option Plan (other than on an automatic grant date) will receive, on the date of
such election or appointment, an Automatic  Option Grant to purchase a pro  rata
number  of shares  of Common Stock.  The pro  rata number will  be determined by
multiplying 250 by the number of whole  calendar months between the date of  the
nonemployee director's election or appointment and the next automatic grant date
and the option price per share will be equal to the fair market value of a share
of  Chiron Common Stock on the grant date. Each Automatic Option Grant will have
a term of ten years measured from its grant date and will be exercisable at  any
time  for all or any part of the  number of granted shares. The shares purchased
under the options are subject to  repurchase by Chiron at the original  exercise
price in the event a nonemployee director ceases to provide service to Chiron or
its  subsidiaries as  a director,  an employee,  a consultant  or an independent
contractor. Chiron's repurchase right will lapse (and the optionee's interest in
the purchased shares will vest) in a series of equal annual installments over  a
five-year  period measured  from the date  of the automatic  grant, provided the
optionee continues  to provide  such services.  Chiron's repurchase  right  will
lapse  in its entirety,  and full vesting  will occur, if,  while providing such
services, the  optionee  dies or  is  permanently  disabled. In  the  event  the
optionee ceases to provide services to Chiron or its subsidiaries as a director,
an  employee,  a consultant  or  an independent  contractor,  the option  may be
exercised for a  period of  three months  after the  date of  such cessation  of
services  (12 months in the case of cessation by reason of disability or death).
Discretionary provisions of the Option Plan are not applicable to the  Automatic
Option  Grants.  On  the  effective  date of  the  Option  Plan,  the  terms and
conditions of outstanding automatic  option grants under  the Chiron 1982  Stock
Option Plan were conformed to the Automatic Option Grants under the Option Plan;
however, the term of the options was not extended.

    Of  the current directors,  Dr. Penhoet and  Dr. Rutter are  not eligible to
receive Automatic Option Grants because they  are employees of the Company.  Mr.
Schuler has waived his right to receive these grants for so long as he serves as
consultant to the Company as described in the following paragraph.

    In  December 1991,  the Company  retained Mr.  Schuler as  a consultant. The
Company agreed to pay  Mr. Schuler $200,000 per  year of consulting, payable  in
monthly  increments, and granted Mr. Schuler options to acquire 40,000 shares of
Chiron Common Stock, vesting on a pro rata basis over four years.

    In May 1992,  the Company  retained Dr. Donald  Glaser to  consult with  and
advise  the  Company in  the  fields of  general  automation and  technology and
neurobiology over a period of three years at an annual retainer of not less than
$45,000.

              INFORMATION CONCERNING BOARD MEETINGS AND COMMITTEES

    The Board of  Directors of  the Company held  a total  of thirteen  meetings
during  the fiscal year ended  December 31, 1994. To  assist in the discharge of
its responsibilities,  the  Board  of Directors  has  designated  four  standing
committees.  They  are a  Finance  and Audit  Committee  (now called  the "Audit
Committee"), a Compensation Committee, an Employee Stock Option Committee and  a
Nominating Committee. The Governance Agreement provides that each such committee
will  generally continue  to have the  same responsibilities as  held before the
Ciba transaction. The number of Investor Directors on each committee (other than
the Nominating Committee)  will generally be  the same proportion  of the  total
membership  of such  committee as  the number  of Investor  Directors is  of the
entire Board of Directors.

    The Audit  Committee is  responsible for  finance, budget,  audit,  internal
control, accounting, and related matters. This Committee, which consisted of Mr.
Coleman,  as Chairman, and Dr. Amelio, held  five meetings in the Company's last
fiscal year. At the  first Board meeting after  the Ciba transaction, the  Board
added  Dr. Krauer to  the Audit Committee and  reappointed the Committee's other
members.

    In May 1992, the Board of Directors consolidated its stock option committee,
compensation committee and employee stock purchase plan committee into a  single
Compensation   Committee.  The   members  of  the   Compensation  Committee  are
nonemployee directors and are ineligible to  participate in any of the plans  or
programs  which  are administered  by the  Committee. The  Committee's principal
functions are to evaluate the  performance of the Company's executive  officers,
to consider and plan for executive officer succession,

                                       9
<PAGE>
to  review  and  approve  executive  compensation,  to  review  the  design  and
competitiveness of the Company's compensation plans generally and to  administer
the  Company's stock option  and stock purchase  plans pursuant to  the terms of
those plans. This  Committee, which consisted  of Dr. Amelio,  as Chairman,  and
Drs.  Strijkert and Schramek and Mr. Coleman prior to the Ciba transaction, held
four meetings in  the Company's  last fiscal year.  At the  first Board  meeting
after  the Ciba  transaction, the  Board added Dr.  Krauer to  the Committee and
reappointed the Committee's other  members. The Board has  also delegated to  an
Employee  Stock Option Committee, composed of Drs. Penhoet and Rutter, authority
to make  routine  stock option  grants  calculated according  to  the  policies,
procedures  and methodologies  approved from  time to  time by  the Compensation
Committee to any employee or consultant except executive officers and directors.

    In February 1994, the Board of Directors established a Nominating Committee.
The Nominating Committee is responsible  for matters relating to composition  of
the  Board of Directors including  recruitment, nomination and succession. Under
the terms of the Governance  Agreement, the Nominating Committee will  initially
be  comprised  of two  Independent Directors,  one  Management Director  and one
Investor Director. After the fifth anniversary of the Closing, so long as Ciba's
Percentage Interest is at least 40 percent, an additional Investor Director will
serve on the Nominating  Committee. While the Nominating  Committee will act  by
the  vote of a majority  of its members, the  Governance Agreement provides that
after the  fifth  anniversary of  the  Closing,  so long  as  Ciba's  Percentage
Interest  is  at  least  40  percent, the  Management  Director  serving  on the
Nominating Committee will  not be able  to break  any tie vote  between all  the
Investor  Director members,  on the one  hand, and all  the Independent Director
members, on the other hand. In  addition, after the eleventh anniversary of  the
Closing,  so long  as Ciba's  Percentage Interest  is at  least 49  percent, the
Governance  Agreement  provides  that  the  Investor  Director  members  of  the
Nominating Committee will have a deciding vote to break any tie vote between all
the Investor Director members, on the one hand, and all the Independent Director
members,  on the other hand (meaning that, with respect to any motion before the
committee, if  the  two Investor  Director  members vote  one  way and  the  two
Independent  Director  members vote  the  other way,  the  vote of  the Investor
Directors will control).  No procedure  has been established  by the  Nominating
Committee  for  the  consideration  of  nominees  recommended  by  stockholders.
However, stockholders of Chiron are entitled to nominate candidates for director
at the Annual Meeting if they  have complied with the advance notice  procedures
contained  in the  Company's Bylaws. The  Nominating Committee  consisted of Dr.
Amelio, Mr. Coleman, Dr. Rutter and  Mr. Schuler prior to the Ciba  transaction.
At  the first  Board meeting  after the  Ciba transaction,  the Board  added Dr.
Krauer to the Committee, Mr. Schuler stepped down and the Board reappointed  the
Committee's other members.

    The  Governance Agreement also contemplates the  creation in the future of a
Strategic Planning Committee with certain responsibilities, described below. The
Governance Agreement provides that the Board  of Directors will set and  approve
measurement standards to evaluate the Company's performance for each fiscal year
of  the Company.  The Governance Agreement  further provides  that the Strategic
Planning Committee of the  Board of Directors will  function from and after  any
fiscal  year  for which  the Company  fails to  meet the  applicable measurement
standards and will continue  to function until the  measurement standards for  a
subsequent  full  fiscal year  are fulfilled.  The Strategic  Planning Committee
will, under the terms of the Governance Agreement, prepare and recommend to  the
Board of Directors a remedial plan intended to restore the Company to compliance
with  applicable measurement standards.  In the event the  Company fails to meet
the measurement  standards  for two  consecutive  fiscal years,  the  Governance
Agreement  provides  that  thereafter  until  the  measurement  standards  for a
subsequent full fiscal year are  fulfilled, in addition to the  responsibilities
of  the  Strategic Planning  Committee described  above, the  Strategic Planning
Committee will have the  delegated power of  the Board of  Directors to set  the
compensation  and  terminate the  employment of  the  executive officers  of the
Company. Under the  terms of  the Governance Agreement,  the Strategic  Planning
Committee  will be comprised of the  three Investor Directors, three Independent
Directors and one  Management Director. While  the Strategic Planning  Committee
will  act by  the vote of  a majority  of its members,  the Governance Agreement
provides  that  the  Management  Director  serving  on  the  Strategic  Planning
Committee  will  not be  able to  break any  tie vote  between all  the Investor
Director members, on the one hand, and all the Independent Director members,  on
the other hand.

                                       10
<PAGE>
    Each  director attended more than 75  percent of the combined total meetings
of the Board of Directors and its Committees on which the director served at any
time during the year.

                             EXECUTIVE COMPENSATION

    The following table sets  forth certain summary  information for the  fiscal
years  ended December 31, 1992, 1993 and 1994 concerning compensation paid to or
accrued by the Company  on behalf of,  those persons who  were, at December  31,
1994,  (i)  the chief  executive officer  and  (ii) the  other four  most highly
compensated executive officers of the Company:

                           SUMMARY COMPENSATION TABLE

<TABLE>
<CAPTION>
                                                                                                LONG-TERM
                                                                                              COMPENSATION
                                                                                             ---------------
                                                        ANNUAL COMPENSATION                      AWARDS
                                        ---------------------------------------------------  ---------------
                                                                              OTHER ANNUAL     SECURITIES        ALL OTHER
                                                                              COMPENSATION     UNDERLYING      COMPENSATION
     NAME AND PRINICPAL POSITION          YEAR     SALARY ($)    BONUS ($)        ($)          OPTIONS (#)        ($)(1)
- - --------------------------------------  ---------  -----------  -----------  --------------  ---------------  ---------------
<S>                                     <C>        <C>          <C>          <C>             <C>              <C>
Edward E. Penhoet ....................       1994   $ 373,338    $ 300,000    $    --              35,000        $   4,500
 President and Chief Executive Officer       1993     323,122      247,754         --              32,000            7,075
                                             1992     299,300      225,000         --              25,000            6,866
William J. Rutter ....................       1994     373,334      300,000         --              35,000            4,500
 Chairman                                    1993     322,917      247,754         --              32,000            7,075
                                             1992     322,659      225,000         --              25,000            6,866
William G. Green .....................       1994     311,000      200,000         --              10,000            4,500
 Senior Vice President, Secretary and        1993     299,621      125,750         --              17,400            7,075
 General Counsel                             1992     285,411      100,000         --                   0            6,866
Dennis L. Winger .....................       1994     248,800      150,000         --              10,000            4,500
 Senior Vice President, Finance and          1993     238,750      124,860         --              13,900            6,862
 Administration, and Chief Financial         1992     222,083      140,000         --                   0            5,301
 Officer
David W. Martin (2) ..................       1994     265,000      101,400    $  81,852(3)         30,000            4,500
 Senior Vice President; President,
 Chiron Therapeutics
<FN>
- - ------------------------------
(1)  "All Other Compensation" includes Company contributions under the Company's
     401(k) Plan  on behalf  of each  of the  named executives  to match  pretax
     elective  deferral contributions (included under Salary) made by each named
     executive to such plan.
(2)  Dr. Martin was not employed by the Company until January 1994.
(3)  In 1994, in connection with the  recruitment and relocation of Dr.  Martin,
     the Company paid to and on behalf of Dr. Martin certain relocation expenses
     totalling $81,852.
</TABLE>

                                       11
<PAGE>
                                 OPTION GRANTS

    The following table sets forth certain information regarding grants of stock
options  pursuant to the Company's 1991 Stock Option Plan during the fiscal year
ended December 31, 1994, to the named executive officers. No stock  appreciation
rights were granted under that plan during fiscal year 1994.

                       OPTION GRANTS IN LAST FISCAL YEAR

<TABLE>
<CAPTION>
                                                 INDIVIDUAL GRANTS
                           -------------------------------------------------------------       POTENTIAL REALIZED VALUE
                           NUMBER OF                                                           AT ASSUMED ANNUAL RATES
                           SECURITIES   % OF TOTAL                   MARKET                         OF STOCK PRICE
                           UNDERLYING     OPTIONS                   PRICE ON                       APPRECIATION FOR
                            OPTIONS     GRANTED TO     EXERCISE OR  DATE OF                        OPTION TERM (3)
                            GRANTED    EMPLOYEES IN    BASE PRICE    GRANT    EXPIRATION  ----------------------------------
          NAME               (#)(1)     FISCAL YEAR     ($/SH)(2)    ($/SH)      DATE     0% ($)(4)     5% ($)     10% ($)
- - -------------------------  ----------  -------------   -----------  --------  ----------  ----------  ----------  ----------
<S>                        <C>         <C>             <C>          <C>       <C>         <C>         <C>         <C>
Edward E. Penhoet........    35,000         3.05%      $   78.125   $78.125     2/18/04   $ 275,157   $1,719,634  $4,357,890
William J. Rutter........    35,000         3.05%          78.125    78.125     2/18/04     275,157    1,719,634   4,357,890
William G. Green.........    10,000         0.87%          78.125    78.125     2/18/04      78,605      491,324   1,245,111
Dennis L. Winger.........    10,000         0.87%          78.125    78.125     2/18/04      78,605      491,324   1,245,111
David W. Martin..........    30,000         2.62%          83.125    83.125     1/03/04     197,627    1,568,305   3,924,395
<FN>
- - ------------------------------
(1)  The  options become exercisable as  to 25 percent of  the granted shares on
     the first anniversary of the date of  grant and, for the balance, in  equal
     monthly  installments  over  the  36-month period  thereafter,  so  long as
     service with  the Company  or one  of its  subsidiaries continues.  To  the
     extent not already exercisable, the options generally become exercisable in
     the  event of an  agreement to dispose  of all or  substantially all of the
     assets or  outstanding capital  stock  of the  Company  by means  of  sale,
     merger,  reorganization or liquidation. However, an outstanding option will
     not be so accelerated if,  in connection with such corporate  transactions,
     the  option  is either  assumed  or replaced  with  a comparable  option to
     purchase shares of capital stock of the successor corporation. With respect
     to the shares of Common Stock subject  to each such option with respect  to
     which  the option first  becomes exercisable after  1995, each optionee was
     granted the right, subject  to approval of  stockholders, to surrender  for
     cancellation  that portion of such option relating to 37.33 percent of such
     shares in return for a cash payment  from Ciba equal to (A) the  difference
     between  $117 per  share and  the exercise price  per share  of such option
     multiplied by (B) the number of shares with respect to which such option is
     so surrendered and  canceled. See  "Proposal 2: Approval  of Amended  Stock
     Option Plan."
(2)  Upon   exercise,  the  exercise  price  and  any  related  tax  withholding
     obligations may  generally  be  paid  in  cash,  or,  in  the  Compensation
     Committee's  discretion, in shares of Common Stock held by the optionee for
     the requisite period to avoid a  charge to Chiron's earnings and valued  as
     of  the exercise date, or  under certain conditions from  the proceeds of a
     same day  sale of  the shares  acquired upon  exercise of  the option.  The
     Compensation  Committee may also  assist an optionee in  the exercise of an
     option by authorizing a  loan from the Company  for the purchase price  and
     related tax obligations.
(3)  In  accordance  with Securities  and Exchange  Commission rules,  there are
     shown hypothetical  gains or  "option  spreads" that  would exist  for  the
     respective  options. These rules require that the gains be based on assumed
     rates of annual  compounded stock price  appreciation of 5  percent and  10
     percent  from  the date  the options  were granted  over the  full ten-year
     option term. If these assumed rates of appreciation occur, the market price
     of Chiron Common Stock in  the year 2004 would  be $127.26 and $202.64  per
     share, respectively, at 5 percent and 10 percent annual compounded rates of
     appreciation  regarding option grants to Drs. Penhoet and Rutter, Mr. Green
     and Mr.  Winger and  $135.40  and $213.94  per  share, respectively,  at  5
     percent  and 10 percent  annual compounded rates  of appreciation regarding
     the option granted  to Dr.  Martin. There can  be no  assurance that  these
     assumed rates of appreciation or any appreciation will occur.
(4)  The   amounts  shown  in  the  table  under  the  assumed  annual  rate  of
     appreciation of 0% for the option  term are based upon the assumption  that
     each  optionee  will  elect  to  surrender  for  cancellation  the greatest
     possible portion of the option grant in consideration for the special  cash
     payment  from Ciba  described in  footnote 1 of  this table.  For the other
     assumed annual rates of  appreciation listed in  the table, the  disclosure
     assumes that such option portion is not surrendered for cancellation, since
     such  a surrender would  realize less gain  than exercise of  the option at
     such assumed annual rates of appreciation.
</TABLE>

                                       12
<PAGE>
               OPTION EXERCISES AND FISCAL YEAR-END OPTION VALUES

    The following table provides information with respect to the named executive
officers as to option exercises by them in fiscal year 1994 and the  unexercised
options  held by  them at  the end  of fiscal  year 1994.  No stock appreciation
rights were exercised in fiscal year 1994.

   AGGREGATED OPTION EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END OPTION
                                     VALUES

<TABLE>
<CAPTION>
                                                                  NUMBER OF SECURITIES        VALUE OF UNEXERCISED
                                                                 UNDERLYING UNEXERCISED           IN-THE-MONEY
                                                  VALUE          OPTIONS AT FY-END (#)      OPTIONS AT FY-END ($)(2)
                            SHARES ACQUIRED      REALIZED     ----------------------------  -------------------------
          NAME              ON EXERCISE (#)       ($)(1)      EXERCISABLE   UNEXERCISABLE   EXERCISABLE UNEXERCISABLE
- - -------------------------  -----------------  --------------  -----------  ---------------  ----------  -------------
<S>                        <C>                <C>             <C>          <C>              <C>         <C>
Edward E. Penhoet........         25,000        $1,297,875       144,149         87,851     $8,095,750   $ 2,517,790
William J. Rutter........         --                --           199,149         87,851     11,842,625     2,517,790
William G. Green.........         --                --            82,554         34,846      3,634,943       944,047
Dennis L. Winger.........         --                --            95,502         18,398      5,651,235       227,094
David W. Martin..........         --                --                 0         30,000              0             0
<FN>
- - ------------------------------
(1)  Value realized is equal to market price of shares on date of exercise  less
     exercise price.
(2)  Value  is calculated  based on  market price  of shares  at fiscal year-end
     ($80.125), less exercise price. With respect to the shares of Common  Stock
     subject to each such option with respect to which such option first becomes
     exercisable  before or  after 1995,  each optionee  was granted  the right,
     subject to approval  of stockholders, to  surrender for cancellation,  that
     portion  of such option relating to 37.33  percent of such shares in return
     for a cash payment from Ciba equal  to (A) the difference between $117  per
     share and the exercise price per share of such option multiplied by (B) the
     number  of shares with respect  to which such option  is so surrendered and
     canceled.  See  "Proposal  2:  Approval  of  Amended  Stock  Option  Plan."
     Including  the  amount that  could be  realized upon  the exercise  of such
     right, the fiscal year-end value would be as follows for each of the  named
     executive   officers:  Edward  E.   Penhoet:  Exercisable  --  $10,080,178,
     Unexercisable -- $3,008,117; William J. Rutter: Exercisable -- $14,584,207,
     Unexercisable -- $3,008,117; William  G. Green: Exercisable --  $4,771,468,
     Unexercisable  -- $1,103,420; Dennis L.  Winger: Exercisable -- $6,065,976,
     Unexercisable -- 369,421; David W. Martin: Exercisable -- $0, Unexercisable
     -- $197,627.
</TABLE>

                               PENSION AGREEMENTS

    The Company has entered into supplemental pension agreements with two  named
executives: William G. Green and Dr. William J. Rutter.

    Mr.  Green's supplemental  pension agreement is  a monthly  benefit for life
beginning at  age  60.  The benefit  is  based  on an  initial  contribution  of
$110,000,  plus an annual contribution for each  year of service until Mr. Green
is age 60, such that the annual contribution when added to the maximum  employee
and Company matching contribution under the Company's 401(k) Plan and any future
retirement  benefit  shall  not  be  less than  $20,000.  This  amount  shall be
increased by an assumed 7 percent interest rate compounded annually. Taking into
account  certain  assumptions  about  Internal  Revenue  Code  limitations,  and
assuming Mr. Green makes the maximum 401(k) contribution under the Chiron 401(k)
Plan,  and receives the  maximum matching contribution  each year, the actuarial
equivalent of Mr. Green's benefit at age 65 would be $48,921 annually for life.

    Dr. Rutter's benefit is meant  to indemnify Dr. Rutter,  up to an amount  of
$10,000  in any  twelve-month period, for  any University  of California pension
benefits he loses by  reason of his  change in status  with the University  from
full-time  to part-time. From  age 65, Dr. Rutter  would receive annual payments
for life of approximately  $6,084, increased each year  by a 2.5 percent  annual
cost of living adjustment.

          COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

    As  noted above, during  1994, Chiron's Compensation  Committee consisted of
Drs. Amelio, Strijkert and Schramek and Mr. Coleman.

    Under the  Governance Agreement,  subject to  certain conditions,  Ciba  has
agreed  to  nominate (and,  at the  end  of each  term, renominate)  Dr. Rutter,
Chairman of the Company, for election  to Ciba's Board of Directors. Dr.  Krauer
has  been the Chairman  of the Board  and Chief Executive  Officer of Ciba-Geigy

                                       13
<PAGE>
Limited since 1987. Under the terms  of the Governance Agreement, Dr. Krauer  is
serving   on  Chiron's  Compensation  Committee  as  a  designee  of  Ciba.  See
"Ciba-Geigy Transaction" above at p. 2 and "Related Transactions" below at p. 18
for a further description of Chiron's relationships with Ciba.

           COMPENSATION COMMITTEE REPORT ON EXECUTIVE COMPENSATION(1)

    Decisions on compensation of  the Company's executive  officers are made  by
the  Compensation  Committee  of the  Board  of  Directors. The  members  of the
Compensation Committee during 1994 were  all nonemployee directors. Pursuant  to
Securities and Exchange Commission rules, the Compensation Committee is required
to report its rationale and the considerations that led to fundamental executive
compensation  decisions as to  Dr. Edward Penhoet,  the Chief Executive Officer,
and Dr.  William Rutter,  Mr. William  Green, Mr.  Dennis Winger  and Dr.  David
Martin,  the four executive officers other than  Dr. Penhoet who, for 1994, were
the Company's most highly  paid executives (collectively  with Dr. Penhoet,  the
"Senior Executives").

    Chiron's  executive compensation  program seeks to  accomplish several major
goals:

        - to  motivate  executives  to  achieve  important  business  and
          individual  performance objectives and to reward them when such
          objectives are met;

        - to recruit and subsequently  retain highly qualified  executive
          officers  by offering overall compensation which is competitive
          with  that   offered   for  comparable   positions   in   other
          biotechnology and pharmaceutical companies; and

        - to align the interests of executive officers with the long-term
          interests   of  stockholders   through  participation   in  the
          Company's stock option plan.

    The Compensation  Committee administers  executive compensation  to  support
Chiron's  business  mission  of  becoming a  leading  biotechnology  company. In
general, compensation  and stock  option awards  of executive  officers are  not
determined  by  the  Company's  achievement  of  specific  corporate performance
criteria. Rather, the Committee has  based its decisions regarding  compensation
for  fiscal year 1994 for Dr. Penhoet and executive officers as a group on (i) a
qualitative evaluation of the Company's  overall performance in 1994,  including
the accomplishment of the strategic partnership with Ciba, the value realized by
stockholders  in the related tender offer,  the enhanced prospects for realizing
sustainable  long-term  appreciation  in   stockholder  value  through   further
investment  in the  Company's research  and development  and through partnership
with and support  of Ciba; (ii)  analysis of compensation  programs and  amounts
paid   for   comparable   benchmark  positions   in   other   biotechnology  and
pharmaceutical companies  and  (iii)  subjective assessment  of  each  executive
officer's  individual performance and,  where relevant, the  performance of that
officer's business unit or functional area of responsibility.

    Currently, the  Company's executive  compensation  program consists  of  the
following  components:  base  salary,  annual  variable  cash  compensation  and
long-term incentive opportunities in the form of stock options.

CASH COMPENSATION (SALARY AND VARIABLE COMPENSATION)

    For 1994, the Compensation Committee  continued the Company's approach  that
base  salaries for  executive officers  should be  measured by  reference to the
median (50th  percentile)  of salaries  for  benchmark positions  in  comparable
companies.  Further,  the  Compensation Committee  provided  that  a significant

- - ------------------------
(1) The  material in  this report  and  under the  caption "Common  Stock  Price
    Performance  Graph" are not "soliciting material," are not deemed filed with
    the Securities and  Exchange Commission and  are not to  be incorporated  by
    reference  in any filing of the Company under the Securities Act of 1933, as
    amended, or the Exchange Act whether made  before or after the date of  this
    Proxy  Statement  and  irrespective of  any  general  incorporation language
    therein.

                                       14
<PAGE>
portion of total cash compensation (salary plus variable compensation) should be
in the form of annual variable cash compensation that is "at risk", dependent on
individual, business unit and overall Company performance.

    The Company has retained an independent executive compensation firm in order
to evaluate the appropriateness of the Company's executive compensation program.
That firm  has  provided the  Compensation  Committee with  annual  survey  data
including  analyses of  comparable positions from  a group  of biotechnology and
pharmaceutical companies. The survey information  serves as a general  reference
for  the Company and the Compensation Committee. In addition, survey information
(i) regarding the base salaries of  comparable positions in the survey group  at
approximately the 50th percentile level is used as a reference to assess whether
executive  officer salary  levels generally  are competitive  and (ii) regarding
aggregate cash  compensation of  comparable  positions in  the survey  group  at
approximately  the 75th percentile level is  a factor considered in establishing
the upper  end  of  the  range of  potential  aggregate  cash  compensation  for
executive  officers.  However, because  of many  other factors,  including those
described above and the  inherent lack of  comparability between any  individual
officer's  responsibilities,  performance,  and  value to  the  Company  and the
average information from the survey group, no element of any executive officer's
compensation is  determined solely  or principally  by reference  to the  survey
information.   The  survey  group   included  biotechnology  and  pharmaceutical
companies with median sales for 1994 of approximately $800 million and executive
positions comparable  in level  and  scope of  responsibility to  the  executive
positions  within the Company.  The Common Stock  Performance Graph on  p. 18 of
this Proxy  Statement  provides  stock performance  information  for  groups  of
companies  that include  some, but  not all,  of the  companies included  in the
survey data.  For  1994, the  average  of  all Company  executive  officer  base
salaries was slightly below the median of base salaries for comparable positions
in  the survey  group and  the average  of total  cash compensation  (salary and
variable compensation) for all Company  executive officers was approximately  at
the  median for total  cash compensation for comparable  positions in the survey
group.

LONG-TERM INCENTIVES -- STOCK OPTIONS

    The Compensation  Committee  believes that  stock  option awards  under  the
Company's  1991 Stock Option Plan serve to  align the long-term interests of the
Company's executive  officers  with those  of  its stockholders  and  assist  in
retention of executives.

    Under the Company's 1991 Stock Option Plan, the Company's executive officers
are  eligible to receive grants  of options to purchase  shares of the Company's
Common Stock.  The options  are generally  granted upon  initial employment  and
annually  thereafter with exercise  prices generally equal  to prevailing market
price on the date of grant and, therefore, will have value to the executive only
to the extent  that the market  price for the  Company's stock increases.  Stock
options  generally  become exercisable  or "vest"  in  increments over  four (4)
years, so long as service with the Company continues.

COMMITTEE PROCEDURES AND CONSIDERATIONS REGARDING 1994 EXECUTIVE COMPENSATION

    Annually, in the early part of each fiscal year, the Compensation  Committee
meets  to consider  Company performance  and the  performance of  each executive
officer. For  1994, this  meeting occurred  on  February 23  and 24,  1995.  The
Committee  reviewed the performance  of the Company  and the executive officers,
other than the Senior Executives, and approved the base salary for 1995 and  the
variable  compensation for performance  in 1994 for each  of them. The Committee
then sought input from Drs. Penhoet and Rutter, the Chief Executive Officer  and
the  Chairman of the Board, and other officers of the Company, as to performance
evaluations and compensation for each  Senior Executive other than Drs.  Penhoet
and  Rutter. The Committee met in  executive session to consider the performance
of Dr. Penhoet and each  of the Senior Executives.  The Committee also met  with
the  remaining members of the Board on February 24, 1995 to consider further the
performance of Drs.  Rutter and Penhoet.  The Committee then  approved the  base
salary  for 1995 and the variable compensation  for performance in 1994 for each
of the Senior Executives. Similar meetings  occurred in February 1994 to  review
performance  for 1993  and determine  each executive  officer's base  salary for
1994.

                                       15
<PAGE>
    Base salaries for executive officers, including the Senior Executives,  were
established   by  the  Compensation  Committee   after  considering  the  survey
information concerning  corresponding elements  of compensation  for  comparable
positions  from the survey  group of companies,  as described above,  as well as
subjective criteria as to individual, business unit and Company performance.

    For 1994, the  Compensation Committee concluded  that the Company's  overall
performance  in  1994 justified  the  favorable consideration  of  all executive
officers, including Dr. Penhoet,  for the awards  of variable compensation.  The
principal  factors which were  then used to fix  each officer's individual award
were a  subjective analysis  of  that individual's  performance and  the  survey
information  concerning  corresponding elements  of compensation  for comparable
positions from the survey group of companies, as described above.

    The Compensation Committee, acting on  the recommendation of an  independent
compensation  consulting firm, granted options  to executive officers, including
the Senior Executives, in 1994. The amounts of such option grants to the  Senior
Executives  are set out in  the option grant table on  page 12. In making annual
grants for  1994  to executive  officers,  the  Committee took  into  account  a
subjective  evaluation  of  individual  and business  unit  performance  by each
executive officer  and  the  expected future  contributions  of  each  executive
officer.  The Committee did not consider, in  determining the size of the option
awards, the amounts of options already outstanding or previously granted and the
aggregate size of the current awards.

CHIEF EXECUTIVE OFFICER COMPENSATION

    While Dr. Penhoet has the title President and Chief Executive Officer,  many
senior  managerial responsibilities are shared  between Drs. Penhoet and Rutter.
Effective February  1, 1994,  the Compensation  Committee had  approved for  Dr.
Penhoet a salary for 1994 of $375,000, representing an increase of approximately
15  percent  and,  on  February  24, 1995,  the  Committee  approved  a variable
compensation award for 1994 for Dr. Penhoet of $300,000. The Committee fixed the
base salary and variable compensation of  Dr. Penhoet after considering (i)  his
steady  and  dedicated  work  in building  long-term  stockholder  value through
employee development and skillful management of valuable technologies, (ii)  his
outstanding management guidance during an especially busy year, in particular in
forming  the  Ciba  alliance  and  (iii) his  ability  to  work  effectively and
harmoniously with the  Chairman and  the Board  and many  external and  internal
constituencies.  Effective February 1, 1994, the Compensation Committee approved
for Dr.  Rutter a  salary for  1994  of $375,000,  representing an  increase  of
approximately  15 percent  and, on February  24, 1995, the  Committee approved a
variable  compensation  award  for  1994   for  Dr.  Rutter  of  $300,000.   The
Compensation  Committee's  decisions  regarding Dr.  Rutter's  compensation were
based upon his  strategic vision and  leadership of the  Company. The  Committee
also  considered corresponding elements of compensation for comparable positions
from the survey group  of companies. The base  salary and total compensation  of
each of Drs. Rutter and Penhoet were below the median of such group.

    As described above, the Compensation Committee, acting on the recommendation
of  an independent compensation consulting firm,  granted options to Dr. Penhoet
and other Senior Executives in 1994, in the amounts set out in the option  grant
table  on p.  12. The  award to Dr.  Penhoet was  based on,  among other things,
information on his total compensation as well as a subjective assessment of  his
past  performance  and his  anticipated  future contributions  to  the Company's
attainment of its long-term business goals.

    As indicated in  the option  exercise table  on p.  13 above,  in 1994,  Dr.
Penhoet  exercised stock  options that  were granted  to him  in 1987  and which
expire in 1997. The options had an exercise price per share equal to the  market
price  of a  share of the  Company's Common Stock  on the date  the options were
granted, and became  exercisable or  "vested" in increments  with Dr.  Penhoet's
continued  employment with the Company. Thus, the amount realized by Dr. Penhoet
through exercise of the options  resulted directly and solely from  appreciation
in the Company's stock price during his tenure as the chief executive officer of
the Company.

                                       16
<PAGE>
DEDUCTION LIMIT FOR EXECUTIVE COMPENSATION

    Recently  enacted  Section 162(m)  of  the Internal  Revenue  Code ["Section
162(m)"] limits federal income tax deductions  for compensation paid to each  of
the  Chief Executive Officer and the four other most highly compensated officers
of a  public company  to $1  million per  year, but  contains an  exception  for
performance-based compensation that satisfies certain conditions.

    The Company is proposing a 1995 Executive Officer Variable Cash Compensation
Plan  for the approval of  stockholders at the Annual  Meeting (see "Proposal 3:
Approval of 1995  Executive Officer Variable  Cash Compensation Plan"  at p.  33
below)  which it believes  will permit variable cash  compensation awards in the
future to qualify for  the performance-based exception  to the deduction  limit.
The  Company also believes that stock  options granted to its executives qualify
for the performance-based  exception to  the deduction  limit. However,  because
final  regulations have not  been issued under  Section 162(m), there  can be no
assurance that the variable  cash compensation or the  options will so  qualify.
Based  on proposed regulations and  commentary thereto, final regulations issued
under Section  162(m) might  require, as  a condition  to continuing  exemption,
certain changes to the composition of the Compensation Committee that may not be
acceptable  to the Board of Directors, because they would exclude representation
of Ciba. If such regulations  do require such changes  and such changes are  not
made, compensation paid to named executive officers under such stock options and
awards  would generally cease to be exempt from the limitation of Section 162(m)
on and after the first annual meeting of stockholders at which directors are  to
be  elected that is held on or after January 1, 1996. However, compensation paid
under stock  options that  were granted  on or  before February  17, 1993  would
continue to be exempt.

    Certain  cash payments to be made by Ciba to holders of Chiron stock options
on November  20,  1994, including  executive  officers, are  being  specifically
considered  by stockholders for approval at the Annual Meeting (see "Proposal 2:
Approval of Amended Stock Option Plan  -- Special Cash Payments Related to  Ciba
Transaction"  at pp. 29-30 below), but, under proposed regulations issued by the
Internal Revenue Service, will not be exempt from application of Section  162(m)
even if specifically approved by the stockholders.

                                          COMPENSATION COMMITTEE

                                          Gilbert F. Amelio, CHAIRMAN
                                          Lewis W. Coleman
                                          Alex Krauer
                                          Henri Schramek
                                          Pieter J. Strijkert

                                       17
<PAGE>
                      COMMON STOCK PRICE PERFORMANCE GRAPH

    The  graph below compares cumulative total  stockholder return on the Common
Stock of Chiron for the five years ended December 31, 1994, with the  cumulative
total  return on the NASDAQ Global Stock Index, the NASDAQ Pharmaceuticals Stock
Index and the Hambrecht &  Quist Health Care Stock  Index over the same  period.
The  graph assumes $100 were invested on  December 31, 1989, in Chiron, and each
of the three indices, and that dividends were reinvested. On November 21,  1994,
Chiron  and Ciba announced  a series of transactions  through which, among other
things, Ciba would acquire approximately 49.9 percent of the outstanding  Common
Stock  of the  Company, including  the purchase  of up  to 11,860,467  shares of
Chiron Common  Stock  at $117  per  share through  a  partial tender  offer.  On
December  31, 1994,  the tender  offer was  still outstanding.  The tender offer
closed on January 4,  1995 (effective January 1,  1995). The comparisons in  the
graph  are  required  by the  Securities  and  Exchange Commission  and  are not
intended to forecast  or be  indicative of  possible future  performance of  the
Company's Common Stock.

                                 12/31/89 = 100

EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC

<TABLE>
<CAPTION>
                                 1989       1990       1991       1992       1993       1994
<S>                            <C>        <C>        <C>        <C>        <C>        <C>
Chiron Stock                    100.0000   154.3860   244.7368   198.2456   294.7368   282.0175
NASDAQ - Global Stock Index     100.0000    85.0171   135.7082   157.3592   181.1530   175.2528
NASDAQ Pharmaceuticals          100.0000   119.9468   318.7806   265.5303   236.6343   178.3964
H&Q Health Care                 100.0000   144.0185   349.9190   300.0694   233.1971   235.1870
</TABLE>

                              RELATED TRANSACTIONS

    From  April 1987 through December 31, 1994,  Chiron and an affiliate of Ciba
each owned a 50 percent equity interest in The Biocine Company, a joint  venture
partnership  formed  for  vaccine  research. This  joint  venture  contributed 9
percent of Chiron's 1994  revenues. In 1994, Ciba  funded, at Chiron's  request,
Ciba's  50 percent  share of the  venture's expenses  as well as  $15 million of
Chiron's share of the venture's expenses and assumed related losses in  exchange
for  a  preferred interest  in future  profits  and cash  flow from  The Biocine
Company. In 1992, Chiron and Ciba acquired the vaccine business of Sclavo SpA of
Siena, Italy and renamed this business  Biocine SpA. Through December 31,  1994,
Chiron  and Ciba each owned 50 percent of  Biocine SpA and shared equally in its
management, profits and losses and capital funding requirements.

    In November 1994, Chiron and Ciba entered into an Investment Agreement  (the
"Investment   Agreement")  which  provided  for  the  creation  of  a  strategic
partnership between the  two companies  and a partial  tender offer  by Ciba  to
purchase  approximately 38 percent of the Company's outstanding Common Stock and
the sale by Ciba to Chiron of its interests in The Biocine Company and J.V.  Vax
B.V. as well as all of the

                                       18
<PAGE>
issued  and  outstanding shares  of Ciba  Corning  Diagnostics Corp.  ("the Ciba
Biocine Business" and "CCD Shares"), in  consideration for which Chiron sold  to
Ciba  6,600,000 shares of Chiron Common Stock and made a cash payment to Ciba of
$24 million. The partial  tender offer by  Ciba and sale to  Chiron of the  Ciba
Biocine  Business and  CCD Shares were  completed on January  4, 1995 (effective
January 1, 1995) (the "Closing").

    The Investment Agreement provides that, after the Closing, Ciba shall  issue
to  a  bank selected  by  Ciba and  reasonably  acceptable to  the  Company (the
"Selected Bank")  a  guarantee  for  the  benefit  of  the  Company  (the  "Ciba
Guarantee") pursuant to which Ciba will guarantee for the benefit of the Company
a  credit facility provided  by the Selected  Bank. The principal  amount of the
Credit Facility  that  may be  outstanding  at any  time  is $425  million  (the
"Maximum  Borrowing Amount"), except that the  Maximum Borrowing Amount shall be
reduced by $1.50 for each $1.00 in additional funding (up to $50 million in such
additional funding) requested by the Company under the Research and  Development
Support  Agreement  described below.  The  Company shall  repay  any outstanding
amounts under the Credit Facility to the extent such amounts exceed the  Maximum
Borrowing  Amount. The Company may not borrow  or reborrow any amounts under the
Credit Facility after the fifth anniversary  of the Closing unless Ciba and  the
Company otherwise agree.

    The  Investment  Agreement  provides further  that  simultaneously  with the
issuance of  the  Ciba  Guarantee,  the Company  shall  execute  and  deliver  a
reimbursement  agreement (the  "Reimbursement Agreement") pursuant  to which the
Company will agree to reimburse Ciba for  any payments made by Ciba pursuant  to
the  Ciba Guarantee as  well as all reasonable  out-of-pocket costs and expenses
incurred  by  Ciba  in  connection  with  the  Ciba  Guarantee.  The   Company's
obligations  under the Reimbursement  Agreement will be  fully collateralized by
any collateral, including equity securities  of the Company, that is  reasonably
acceptable  to Ciba.  The Reimbursement Agreement  also will  contain a negative
pledge covenant  with  respect  to  the collateral  and  such  other  terms  and
conditions as are customary to reimbursement agreements of its type.

    Pursuant  to  the Investment  Agreement, as  soon  as practicable  after the
Closing, Ciba and  the Company  shall negotiate  in good  faith the  terms of  a
Research  and Development Support  Agreement, which shall  contain the following
terms: (i)  during  the period  commencing  on January  1,  1995 and  ending  on
December  31,  1999 (the  "Funding Period"),  the Company  shall be  entitled to
present from time to time proposals for research and development programs  ("R&D
Ventures")  that the Company shall  desire Ciba to fund  or partially fund; (ii)
subject to the  limitations set forth  below, Ciba  will fund its  share of  all
development  costs of R&D Ventures,  which shall be 100  percent, or such lesser
amount as  the parties  may agree  (but not  in excess  of the  maximum  funding
provided  for in the Investment Agreement); (iii) the obligation of Ciba to fund
R&D Ventures shall  be subject  to the following  limitations: (a)  in no  event
shall  Ciba be obligated to provide funding  to the Company in any calendar year
during the Funding Period  for R&D Ventures  in an amount in  excess of (x)  $75
million  in 1995 and (y) for calendar years thereafter, in equal annual portions
of the remaining  unexpended aggregate  amount under (b)  below; and  (b) in  no
event  shall (x) the aggregate amount of funding provided to the Company by Ciba
LESS (y) the aggregate amount  of any payments to or  profits paid or earned  by
Ciba  in connection with any product or products developed in any R&D Venture at
any time during the Funding Period exceed $250 million; provided, however,  that
such amount may be increased, at the Company's request, to up to $300 million in
consideration  of a reduction in the Maximum Borrowing Amount (as defined above)
at the rate  of $1.00  of increased research  and development  funding for  each
$1.50  reduction of  the Credit Facility;  (iv) in consideration  of the funding
provided by Ciba  for the  R&D Ventures, and  subject to  the Company's  buy-out
right   described  below,  but  without   thereby  guaranteeing  the  successful
conclusion of any project included in the R&D Ventures, the Company shall  offer
Ciba  the opportunity to share  in the market opportunities  with respect to any
product or products resulting from the R&D Ventures, which may be in the form of
royalties, profit sharing or participation  in distribution or sales  activities
in  selected geographic markets or otherwise; and (v) the Company shall have the
right, but not the obligation, with respect to R&D Ventures to repurchase all of
the rights granted to Ciba upon tender by the Company to Ciba of payment in  the
amount  of the Buyout Amount (as described below)  in effect at the time of such
payment for R&D Ventures; provided that  such right shall expire if such  tender
is not made prior to January 1, 2002. The "Buyout Amount" means, as of any time,
the amount equal to (i) the sum of all R&D

                                       19
<PAGE>
funding  payments made by  Ciba to the Company  prior to such  time, PLUS (ii) a
reasonable return on such payments which shall be agreed to by the parties  upon
commencement  of the research and development  program and which shall represent
the time of value of money, LESS  (iii) the aggregate amount of all payments  or
profits received by Ciba in connection with R&D Ventures, LESS (iv) a reasonable
return  on such  payments which  shall represent  the time  value of  money. The
Company shall be entitled to make the  payment of the Buyout Amount in the  form
of cash or Common Stock, or a combination of the two.

    Ciba   and  the  Company   have  also  entered   into  the  Cooperation  and
Collaboration  Agreement  regarding  research  and  development  collaborations,
marketing  and manufacturing  arrangements, access  of each  party to  the other
party's technology and reciprocal most  favored nation rights regarding  certain
licenses.  Each  party will  be  the preferred  collaborator  of the  other with
respect to research and development projects and activities in specific areas of
identified interest.  Under the  Cooperation and  Collaboration Agreement,  each
party  has a right of first negotiation  with respect to collaborations with the
other party regarding certain research and development projects. The first  such
collaboration   project  contemplated  by  the  parties   is  in  the  field  of
combinatorial chemistry. Neither party to such agreement, has the right to enter
into  any  material  research  and  development  collaboration  related  to  the
Company's  strategic mission  with any  third party  if such  third party's only
material contribution to  the collaboration  is expected to  be funding,  unless
such  party has first  offered the other  party hereto the  opportunity to enter
into such collaboration  on the same  terms as such  third party, provided  that
such  restrictions shall not apply to collaborations with non-commercial sources
of funding, including grants, or to financing arrangements with third parties in
which the  consideration to  the third  party  is the  return on  financing.  In
addition,  under the Cooperation  and Collaboration Agreement,  the parties have
(x) a  reciprocal right  of  first refusal  with  respect to  marketing  certain
products  developed by the other party or  with respect to which the other party
has the right to  market and (y)  a reciprocal right  of first negotiation  with
respect  to manufacturing certain products developed  by the other party or with
respect to which the other party has the right to manufacture.

    Under the Governance Agreement, so long  as Ciba has the right to  designate
for nomination at least one Investor Director, subject to certain exceptions, if
the  Board of Directors  authorizes the issuance of  any Equity Securities after
the Closing, Ciba will  have the right  to purchase its Pro  Rata Share of  such
securities.  As used herein,  "Pro Rata Share"  means the fraction  of an entire
issuance of securities, the numerator of which shall be the number of shares  of
Common  Stock owned by Ciba  and its affiliates (other  than the Company and its
subsidiaries) immediately  prior to  such issuance  of such  securities and  the
denominator  of which shall  be the aggregate  number of shares  of Common Stock
outstanding immediately prior to such issuance of such securities. If Ciba shall
elect to purchase any such securities,  such securities will be issued and  sold
to  Ciba by the Company at the same time and on the same terms and conditions as
the new securities are issued  and sold to third  parties (except that, if  such
securities are issued for consideration other than cash, Ciba shall pay the fair
market value thereof, as determined in accordance with the Governance Agreement.

    Ciba  and  the  Company  have  also entered  into  the  Market  Price Option
Agreement pursuant  to  which Ciba  shall  have  the right  to  purchase  shares
directly  from the Company under the  circumstances described below. Pursuant to
the  Market  Price  Option  Agreement,  the  Company  granted  to  Ciba  Biotech
Partnership,  Inc.  (hereinafter  "Ciba  Biotech")  an  irrevocable  option (the
"Option") to purchase on each exercise closing date, on the terms and subject to
the conditions set forth therein, up  to the number of newly-issued shares  (the
"Option  Shares") equal, as of the related  Exercise Date (as defined below), to
the number of Shares that Ciba would be permitted to purchase from persons other
than the Company as of such Exercise Date under the Governance Agreement.

    The Market Price Option Agreement provides that the Option may be  exercised
by  Ciba Biotech (or  its designee, which designee  must be Ciba  or a direct or
indirect wholly owned subsidiary of Ciba), in whole or in part, at any time,  or
from  time  to time  (the date  of any  such  exercise being  referred to  as an
"Exercise Date"), during the period beginning upon the Closing and ending on the
date  that  Ciba  and  its  affiliates  become  the  beneficial  owners  of  all
outstanding  shares of Equity  Securities, so long as  an Exercise Condition (as
defined below) shall exist on such  Exercise Date; provided, however, that  Ciba
Biotech may not exercise the Option at any time unless it owns Equity Securities
representing at least 30 percent of the aggregate

                                       20
<PAGE>
number  of votes entitled to be voted in an election of directors of the Company
by all the outstanding voting stock.  The Option may be repeatedly exercised  by
Ciba Biotech; provided, however, that each exercise of the Option for fewer than
the maximum number of Shares then issuable pursuant to an exercise of the Option
shall  be for at least that number of shares that results in a purchase price of
$1 million.

    Pursuant to the Market Price Option Agreement an "Exercise Condition"  shall
exist  if  any  of the  following  conditions  are satisfied:  (i)  Ciba Biotech
concludes that  it  is  in  any  way legally  (including  as  a  result  of  any
regulation)  restricted  from  purchasing  or  otherwise  acquiring  any  Equity
Securities from any  person other  than the Company,  including any  restriction
resulting  from Ciba Biotech's possession of any non-public material information
regarding the Company; (ii)  Ciba Biotech concludes  that there is  insufficient
liquidity in the open market to permit it to (A) purchase on the open market the
amount of Equity Securities it desires to purchase within the time period during
which  it desires to make such purchases  or (B) make such purchases within such
time period without  such purchases unduly  affecting the price  of any of  such
Equity  Securities, in which case  the Option may be  exercised to the extent of
such insufficient  liquidity as  determined  by Ciba  Biotech, or  (iii)  Ciba's
Percentage  Interest  is  below 50  percent  and  Ciba Biotech  desires,  and is
permitted under the Governance Agreement, to increase Ciba's Percentage Interest
to a percentage exceeding 50 percent; provided  that if as of any Exercise  Date
the  only existing Exercise Condition is the condition specified in clause (iii)
above, then Ciba Biotech shall not  purchase through the exercise of the  Option
on  such  date any  Shares  that would  increase  Ciba's Percentage  Interest to
greater than 51 percent. The purchase price for any Shares purchased pursuant to
an exercise of  the Option  shall be  the Fair Market  Value of  such shares  as
defined in the Market Price Option Agreement.

    Ciba  and  the Company  have also  entered  into the  Subscription Agreement
pursuant to which the Company shall have the right, exercisable at any time  and
from  time  to time  during the  eleven  year period  following the  Closing, to
require Ciba Biotech to  acquire Common Stock of  the Company directly from  the
Company  at Fair Market Value (as defined  below) up to the Subscription Amount.
"Subscription Amount" means, initially $500 million, and thereafter, such amount
as reduced by the aggregate  price paid from time to  time after the Closing  by
Ciba  Biotech or any of  its affiliates to the Company  or any subsidiary of the
Company for each purchase from the Company  or any subsidiary of the Company  of
any  Equity Securities of  the Company by  any of them,  whether pursuant to the
Market Price  Option  Agreement,  the  Governance  Agreement,  the  Subscription
Agreement  or  otherwise  except  for  (i)  purchases  by  Ciba  Biotech  or its
affiliates in connection with collaborations entered into by Ciba Biotech or its
affiliates and the Company in accordance  with the terms of the Cooperation  and
Collaboration  Agreement  or  (ii)  Equity  Securities  issued  to  Ciba  or its
affiliates in accordance with the terms of the Research and Development  Support
Agreement.  Ciba Biotech's  obligation to  purchase any  shares pursuant  to the
Subscription Agreement will be subject to the satisfaction as of the  applicable
closing date of certain conditions.

    The  Governance Agreement provides that the  Company will not enter into any
material transaction with Ciba or any of its affiliates after the Closing (other
than those expressly  contemplated by the  Investment Agreement, the  Governance
Agreement or any other ancillary agreement) unless a majority of the Independent
Directors or holders of a majority of the voting power of the voting stock which
is held by unaffiliated stockholders approve such transaction.

    Under  the  terms of  the Investment  Agreement, all  holders of  options to
acquire shares of Common Stock under Chiron's 1991 Stock Option Plan on November
20, 1994,  including  executive officers  and  directors of  the  Company,  were
granted  certain cash  payment rights in  connection with  the Ciba transaction.
These cash payment  rights are discussed  below under "Proposal  2: Approval  of
Amended  Stock  Option  Plan  -- Special  Cash  Payments  Related  to Ciba-Geigy
Transaction" at pp. 29-31  and incorporated into this  section of the  Company's
Proxy  Statement by reference. The Company agreed that if any such cash payments
by Ciba  to Chiron  executive  officers, alone  or  when aggregated  with  other
compensation  payable  to any  such  executive officers,  constitute  an "excess
parachute payment" within the  meaning of Section 280G  of the Internal  Revenue
Code  and/or would subject such  individuals to a tax  under Section 4999 of the
Internal Revenue  Code,  the  Company  may  pay  such  executive  officers  such
additional  amount or amounts as shall be necessary to assure that, on any date,
the  net  after-tax  amount  realized  by  such  executive  officers  from   the
compensation  paid  as  a result  of  such  cash payments  from  Ciba  plus such
additional amount shall equal the

                                       21
<PAGE>
net after-tax amount  that such individuals  would have realized  from the  cash
payment  from Ciba if such additional tax were not imposed. The Internal Revenue
Code's excess parachute provisions generally provide that if parachute  payments
exceed  three times an individual's average  compensation for the five tax years
preceding the  triggering  event,  the  Company  loses  its  deduction  and  the
recipient  is subject to a 20 percent excise tax for the amount of the parachute
payments in excess of such average  compensation. Although the Company does  not
believe that any such cash payment by Ciba would constitute an "excess parachute
payment",  it nevertheless has agreed to  so indemnify its executive officers in
the event that such additional tax is imposed.

    In 1990, the  Company entered into  agreements with Bios  Chile ("Bios"),  a
Chilean  biotechnology  company  in  which  Dr.  Pablo  Valenzuela,  Senior Vice
President, holds an ownership interest.  Dr. Bernardita Mendez, Vice  President,
Regulatory  and  Quality  Affairs, who  is  married  to Dr.  Valenzuela,  is the
daughter of the general manager of  Bios. Under the agreements, as amended:  (a)
Dr. Valenzuela will be permitted to contribute up to 20 percent of his work time
in  any year to Bios; (b) Chiron acquired 19 percent of the outstanding stock of
Bios upon payment of $100,000, plus an option to acquire up to 50 percent of the
outstanding stock  upon  payment of  an  additional $100,000;  (c)  Chiron  will
contribute  equipment to Bios with a value of  $250,000 in the first year of the
agreement and $50,000 a  year for ten  years thereafter; (d)  Chiron will pay  a
maximum  of $25,000 per year for each of the next ten years for reasonable costs
and expenses incurred by Dr. Valenzuela  while performing services for Bios.  In
return,  Bios will perform research services for  Chiron valued at not less than
$200,000 in the first  year of the  agreement and $50,000 a  year for ten  years
thereafter.  Chiron will have the right to commercialize, outside Latin America,
any product of Bios and Bios will have the right to sell certain Chiron reagents
for research purposes. In fiscal year 1994, the Company paid to Bios a total  of
$228,480 under various provisions of the above-mentioned agreements.

    Mr.  Lewis Coleman, a director of the Company, is Chief Financial Officer of
BankAmerica Corp.  During  fiscal year  1994,  the  Company paid  $90,000  to  a
BankAmerica Corp. subsidiary in fees incurred in the ordinary course of business
in connection with the management of a portion of Chiron's investment portfolio.
The  Company also maintains  routine banking relationships  with Bank of America
N.T. & S.A., a  subsidiary of BankAmerica Corp.  The Company believes that  fees
and  costs associated with all of these services are customary and reasonable in
relation to the services rendered.

    In September 1990, Mr. William  Green, Senior Vice President, Secretary  and
General  Counsel, entered into an agreement with the Company which provides that
the Company will maintain life insurance for  him in the amount of $500,000  and
that  in the event Mr. Green's  contributions or premiums associated with health
or dental insurance exceed $4,500 in any year, the Company will pay the  excess.
Mr.  Green's agreement with the  Company further provides that  in the event the
Company terminates his employment without cause, all options to purchase  shares
of  Common Stock of  the Company granted to  Mr. Green on his  date of hire will
immediately vest.

    In March 1993, the Company provided a  loan of $1,000,000 to Dr. William  J.
Rutter,  Chairman of the Board, to assist  him in the renovation of a residence.
The loan bore  an interest  rate equal  to the  average yield  on the  Company's
aggregate  investment portfolio  adjusted quarterly  and was  due in  full on or
prior to March 3, 1998. The  loan was secured by a  second deed of trust on  the
property  and a  pledge of  stock whereby Dr.  Rutter granted  Chiron a security
interest in 45,000 shares of Chiron Common  Stock owned by him. On December  30,
1994,  Dr. Rutter repaid in full the  amount outstanding on the loan. During the
fiscal  year  ended  December  31,   1994,  the  largest  aggregate  amount   of
indebtedness outstanding on the loan was $1,032,031.

    The  Company  has  made several  loans  to  Dr. Dino  Dina,  Vice President,
Vaccines Research, and  President, The  Biocine Company,  to assist  him in  the
rebuilding  of  his  residence following  its  destruction in  the  October 1991
Oakland/Berkeley fire and pending resolution of insurance coverage disputes. The
first loan, made in 1992, was for $400,000 at a variable prime interest rate and
was due in  full on or  prior to September  11, 1995. The  second loan, made  in
December  1992 and January 1993, was for a total of $200,000 at a variable prime
interest rate and was due in full on  or prior to December 8, 1995. On April  1,
1993, the

                                       22
<PAGE>
Company  loaned Dr.  Dina an  additional $200,000  at a  variable prime interest
rate. The loan was  due in full  on or prior  to April 1,  1996. The loans  were
secured  by a second deed of trust on the property and a pledge of stock whereby
Dr. Dina granted Chiron  a security interest in  10,000 shares of Chiron  Common
Stock  owned by  him. On  April 12,  1994, Dr.  Dina repaid  in full  the amount
outstanding on the first loan made in 1992 and partially repaid the second loan.
As of December 31, 1994,  the amount outstanding on  the remaining loans to  Dr.
Dina,  including  interest,  was  $294,387.  The  largest  aggregate  amount  of
indebtedness outstanding during the fiscal year  ended December 31, 1994 on  the
three  loans to Dr. Dina  was $864,186. On January 31,  1995, Dr. Dina repaid in
full the amounts outstanding on the two remaining loans.

    Pursuant to the provisions of an executive loan program adopted by the Board
of Directors to promote stock ownership by executive officers, in December 1993,
the Company provided a loan  of $408,000 to Dr. Dina  to enable him to  purchase
34,000  shares of Chiron  Common Stock through  the exercise of  a stock option.
Under the terms of the  program, Dr. Dina agreed: (1)  to pledge to the  Company
34,000  shares of Chiron Common Stock acquired  by him as security for the loan;
(2) that the  shares will be  subject to an  additional restriction on  transfer
which  will lapse as to fifty percent (50  percent) of the shares after one year
and the remainder after two years and (3) that in the event he leaves the employ
of the Company prior to  the lapse of the  transfer restriction, for any  reason
other  than  death  or  permanent  disability,  the  shares  then  subject  to a
restriction on transfer  will be  subject to repurchase  by the  Company at  the
original  stock option exercise price.  The loan bore an  interest rate equal to
the average  yield  on the  Company's  aggregate investment  portfolio  adjusted
quarterly  and was due in full  on or prior to December  8, 1998. As of December
31, 1994, the amount  outstanding on the loan  to Dr. Dina, including  interest,
was $426,571. During the fiscal year ended December 31, 1994, the largest amount
of  indebtedness outstanding on the loan was  $426,571. On January 31, 1995, Dr.
Dina repaid in full the amount outstanding on this loan.

    In October 1993, the Company provided a loan of $1,000,000 to Dr. Edward  E.
Penhoet, President and Chief Executive Officer, to assist him in the purchase of
a  parcel of real property. The loan bore  an interest rate equal to the average
yield on the Company's aggregate investment portfolio adjusted quarterly and was
due in full on or prior  to October 21, 1998. The  loan was secured by a  second
deed  of trust on the property. As additional security for the loan, Dr. Penhoet
agreed to transfer to the Company, when acquired, stock underlying vested  stock
options  to  purchase 30,651  shares  of Chiron  Common  Stock held  by  him. On
December 29, 1994,  Dr. Penhoet  repaid in full  the amount  outstanding on  the
loan.  During the  fiscal year  ended December  31, 1994,  the largest aggregate
amount of indebtedness outstanding on the loan was $1,051,262.

    In September 1994, the Company provided a loan of $200,000 to Dr. William J.
Link, Vice President of the Company and Chief Executive Officer of Chiron Vision
Corporation, to assist him in financing his principal residence. The loan has  a
fixed  interest rate of 7.75 percent and is due in full on or prior to September
2, 1999. The loan is secured  by a second deed of  trust on the property. As  of
December  31, 1994, the  amount outstanding on  the loan to  Dr. Link, including
interest, was $203,884. The largest aggregate amount of indebtedness outstanding
during the fiscal  year ended  December 31,  1994 on the  loan to  Dr. Link  was
$203,884.

    In  October 1993, the Company  provided a loan of  $400,000 to Dr. Mickey S.
Urdea, Vice President, Nucleic Acid Systems Research and Development, to  assist
him  in the renovation of a residence. The  loan bears an interest rate equal to
the average  yield  on the  Company's  aggregate investment  portfolio  adjusted
quarterly  and is  due in  full on  or prior  to October  11, 1995.  The loan is
secured by a second deed of trust on the property and a pledge of stock  whereby
Dr.  Urdea granted Chiron a  security interest in 3,105  shares of Chiron Common
Stock held by him. As of December  31, 1994, the amount outstanding on the  loan
to  Dr. Urdea, including interest, was $391,368. The largest aggregate amount of
indebtedness outstanding during the fiscal year  ended December 31, 1994 on  the
loan to Dr. Urdea was $399,288.

    In  February 1994,  in connection with  his recruitment  and relocation, the
Company provided a loan of $450,000 to Dr. David Martin, Senior Vice  President,
and  President,  Chiron  Therapeutics,  to  assist  him  in  the  purchase  of a
residence. The loan bears a variable prime  interest rate and is due in full  on
or  prior to February 9, 1999. The loan is  secured by a second deed of trust on
Dr. Martin's property in Pennsylvania. As

                                       23
<PAGE>
of December  31,  1994,  the amount  outstanding  on  the loan  to  Dr.  Martin,
including  interest, was $458,790. The  largest aggregate amount of indebtedness
outstanding during the fiscal year  ended December 31, 1994  on the loan to  Dr.
Martin  was $461,185. In 1994, in connection with the recruitment and relocation
of Dr.  Martin,  the  Company paid  to  and  on behalf  of  Dr.  Martin  certain
relocation expenses totalling $81,852.

    In  August 1994, the  Company provided a  loan of $200,000  to Mr. Dennis L.
Winger, Senior Vice President and Chief Financial Officer, to assist him in  the
purchase  of real property. The loan bears  an interest rate of 7.25 percent and
is due in full on or prior to June 1, 1996. The loan is secured by a second deed
of trust  on  Mr.  Winger's residence.  As  of  December 31,  1994,  the  amount
outstanding  on the  loan to Mr.  Winger, including interest,  was $200,000. The
largest aggregate  amount of  indebtedness outstanding  during the  fiscal  year
ended December 31, 1994 on the loan to Mr. Winger was $200,358.

    The  Company has indemnification agreements  with directors that (i) confirm
the present indemnity  provided to them  by the Company's  Bylaws and give  them
assurances  that  this indemnity  will continue  to  be provided  despite future
changes in the Bylaws and (ii) provide that, in addition, the directors shall be
indemnified to  the  maximum  extent  permitted  by  law  against  all  expenses
(including  attorneys' fees), judgments, fines,  and settlement amounts incurred
or paid by them in any action or  proceeding, including any action by or in  the
right  of the  Company, on account  of their  service as a  director, officer or
similar official of  any other company  or enterprise when  they are serving  in
such  capacities at the  request of the  Company. The indemnification agreements
further provide that expenses incurred by a director in such cases shall be paid
by the Company in advance, subject to the director's obligation to reimburse the
Company in  the event  it is  ultimately  determined that  the director  is  not
entitled  to be indemnified for such expenses under any of the provisions of the
indemnification agreement.  However,  no  indemnity  will  be  provided  to  any
director  under the agreements as described in clause (ii) of the first sentence
of this  paragraph  on  account of  conduct  which  is finally  adjudged  to  be
knowingly   fraudulent,  deliberately   dishonest,  or   to  constitute  willful
misconduct. In addition, no  indemnification will be provided  if a final  court
adjudication  shall determine  that such  indemnification is  not lawful,  or in
respect of any  suit in which  judgment is  rendered against a  director for  an
accounting  of profits made from a purchase or sale of securities of the Company
in violation of Section 16(b) of the Exchange Act, as amended, or of any similar
statutory provision, or on account of any remuneration paid to a director  which
is  finally adjudged to have been paid  in violation of law. The indemnification
agreements  also  contain  provisions  designed  to  protect  the  Company  from
unreasonable settlements or redundant legal expenditures.

                                  PROPOSAL 2:
                     APPROVAL OF AMENDED STOCK OPTION PLAN

GENERAL

    The  Board of  Directors has  adopted, subject  to stockholder  approval, an
amended Chiron  1991 Stock  Option  Plan ("Plan"  or  "1991 Plan"),  amended  to
include:

    (1) A limit to the number of shares with respect to which awards may be made
under  the Plan to a single individual during  the term of the Plan to 1 million
shares. The limit on the  number of shares with respect  to which awards may  be
made  under  the Plan  to a  single individual  is intended  to assure  that, if
certain other conditions  are satisfied,  stock options  and stock  appreciation
rights  and certain other awards  granted under the Plan  will not be subject to
the $1  million annual  deduction  limit on  executive compensation  imposed  by
Section 162(m) of the Internal Revenue Code, enacted in 1993.

    (2)  The provisions required to implement the Investment Agreement to permit
Ciba to make  certain cash payments  to employees and  directors who held  stock
options  on November 20,  1994. The cash  payment rights allow  holders of stock
options to participate in  the value inherent in  the Ciba tender offer  without
requiring  immediate  exercise  of  their  options.  These  payment  rights  are
described under "Special Cash Payments Related to Ciba-Geigy Transaction".

    In addition, in  August 1993,  the Board adopted  an amendment  to the  Plan
which  did  not  require  stockholder  approval  to  provide  that,  except  for
Substitute   Options   as    defined   in   the    1991   Plan,   Fair    Market

                                       24
<PAGE>
Value  of a  share of  Common Stock  on any  relevant date  will be  the average
between the reported high and reported low price on the date in question of  one
share of Common Stock on the NASDAQ National Marketing System, rather than being
based  on a ten (10)  day average as had previously  been used to determine Fair
Market Value under the 1991 Plan.

    The 1991 Plan was adopted originally by the Board of Directors ("Board")  on
June  14, 1991  and, as  subsequently amended,  was approved  by stockholders on
December 10, 1991 and May 13, 1993.  As of January 1, 1995, approximately  1,639
employees  (including officers  and directors),  63 independent  contractors and
consultants, and  9 nonemployee  directors are  eligible to  participate in  the
Plan. The Plan, as proposed to be amended ("Amended Plan"), is attached as Annex
1,  to which reference is made for  a complete statement of the Plan provisions.
The market price of Chiron  Common Stock on December  31, 1994 was $80.125.  The
following  summary  of  certain amended  Plan  provisions is  qualified,  in its
entirety, by reference to the Amended Plan.

GENERAL DESCRIPTION OF CHIRON 1991 STOCK OPTION PLAN AS AMENDED

    Pursuant to Securities and Exchange Commission rules, the Plan is  described
below in its entirety, incorporating the proposed amendments.

PURPOSE

    The purpose of the Plan is to enable Chiron to attract and retain employees,
including officers and directors, nonemployee directors, independent contractors
and  consultants and  to offer incentives  and rewards that  will encourage such
individuals to acquire a proprietary interest in the Company, and to continue in
the service of the Company and its subsidiaries.

ADMINISTRATION

    The Plan  is administered  by a  committee or  committees (the  "Committee")
appointed  by the Board from among its  members. Administration of the Plan with
respect to officers subject to Section 16 of the Exchange Act will be by members
who are "disinterested persons" as that term is defined in Rule 16b-3 under that
Act. The Committee is generally authorized  to construe and interpret the  Plan,
to establish appropriate rules and regulations, to select employees, independent
contractors   and  consultants   of  the   Company  and   its  subsidiaries  for
participation and to specify the terms of awards granted under the Plan. Members
of the  Committee  may  be removed  by  the  Board. In  determining  the  terms,
conditions and amount of each award, the Committee may take into account various
criteria, including, among others, salary grade and performance of individuals.

    Chiron  will pay all costs of administration  of the Plan. The cash proceeds
received by Chiron from the issuance of shares pursuant to the Plan will be used
for general purposes.

SHARES AND TERM

    The stock subject to  awards granted under the  Plan is Chiron's  authorized
but  unissued or reacquired  Common Stock ("Common  Stock") or shares  of one or
more series of Chiron's authorized but unissued or reacquired Restricted  Common
Stock   (in  the  aggregate,  "Company  Stock").  The  rights,  preferences  and
privileges, together with restrictions and limitations, and the number of shares
of each series of Restricted Common Stock  issuable under the Plan, will be  set
forth in Chiron's Certificate of Determination of Preferences of Common Stock as
in  effect  from time  to time  during the  term  of the  Plan. The  Company may
repurchase shares in the open market or otherwise.

    Initially, the stockholders approved for issuance under the Plan,  4,500,000
shares  of Company Stock in  addition to the shares  of Company Stock previously
authorized  by  stockholders  and  remaining  for  issuance  under  the   Chiron
Corporation 1982 Stock Option Plan ("1982 Plan") and the Chiron Corporation 1984
Non-Qualified Plan ("Non-Qualified Plan") on December 10, 1991 (897,204 shares).
Except  as otherwise  limited by  the terms  of this  Plan, this  amount will be
subject to adjustment annually, without further stockholder approval, commencing
on January  1, 1992,  to  authorize the  grant of  awards  upon that  number  of
additional shares of Company Stock equal to 1.50 percent of the number of Chiron
Common Equivalent Shares outstanding as of the end of the preceding fiscal year.
"Chiron Common Equivalent Shares" are the

                                       25
<PAGE>
total  number of  shares of  Common Stock outstanding  plus the  total number of
shares of  Common Stock  issuable  upon conversion  or exercise  of  outstanding
warrants,  options and convertible securities. Not more than 4,500,000 shares of
Company Stock, plus the number of shares of Company Stock remaining for issuance
under Chiron's 1982 Plan and Chiron's  Non-Qualified Plan on the effective  date
of  this Plan may  be subject to  Incentive Stock Options  ("ISO") granted under
this Plan. In no event will more than 500,000 shares of Restricted Common  Stock
be issued under this Plan.

    To  the extent that  an option expires  or is terminated,  or is canceled or
forfeited for  any  reason  (other  than surrendered  for  a  cash  appreciation
payment)  without having been exercised in  full, any remaining shares allocable
to the  unexercised portion  of such  option shall  again become  available  for
subsequent grants under the Plan. To the extent that a share right or share unit
expires  or is terminated,  or is canceled  or forfeited for  any reason without
being paid in cash or shares of Company Stock, any remaining shares allocable to
the unpaid portion  of such  share right or  share unit  shall become  available
again  for subsequent  grants under the  Plan. Restricted shares  that have been
issued but forfeited or  repurchased by the Company  shall not be available  for
the  grant of new awards under the Plan. Shares attributable to the payment of a
share unit in cash, and the payment of cash or a cash appreciation  distribution
upon the surrender or exercise of a stock option, or the payment of cash in lieu
of  shares under a  restricted share or  a share right,  and shares forfeited or
repurchased by Chiron pursuant to its forfeiture and repurchase rights under the
Plan will not be available for subsequent grants under the Plan.

    Pursuant to one of the amendments that  is the subject of this proposal,  no
individual  may receive awards under the Plan over its term with respect to more
than 1 million shares of Common Stock.

ELIGIBILITY

    Employees,  including   officers  and   directors,  nonemployee   directors,
consultants  and independent contractors of the Company or its subsidiaries, are
eligible to  receive awards  under the  Plan  either as  a reward  for  services
rendered  or as  an incentive to  continue in the  Company's employ. Nonemployee
directors are eligible only for automatic option grants, as described below.

GRANTS TO AWARD HOLDERS OF STOCK OPTIONS, RESTRICTED SHARES, SHARE RIGHTS AND
SHARE UNITS

    The Committee may,  from time to  time, grant  awards to one  or more  award
holders  that it  determines is  eligible to participate  in the  Plan. An award
shall consist of either a stock option,  a restricted share, a share right or  a
share unit.

    In  order to  assist an  award holder  in the  acquisition of  Company Stock
pursuant to an award, the Committee may authorize the Company to extend  secured
or  unsecured credit to the  award holder (other than  pursuant to the automatic
option grant provisions  of the Plan).  The Committee may  also permit an  award
holder  to elect to have shares of the  Company's Common Stock held by the award
holder for the  requisite period  to avoid a  charge to  the Company's  earnings
("Previously  Owned Shares") applied  to satisfy any  withholding tax obligation
incurred in connection with the award and may require or permit a portion of any
Common Stock otherwise issuable  under an award  to be paid  in cash instead  of
stock and applied to such a withholding tax obligation.

    STOCK OPTIONS

    Under the terms of the Plan, the Committee may grant an ISO, which satisfies
the  requirements of  Section 422  of the Internal  Revenue Code  ("Code"), or a
non-statutory option ("NSO"), which is not intended to satisfy the  requirements
of Section 422 of the Code.

    The  Committee may determine the number  of shares of Company Stock issuable
under an  option as  well as  the exercise  date, the  exercise price,  and  the
exercise  period of an option. However, the  exercise price of an option may not
be less  than eighty-five  percent (85  percent) of  the fair  market value  (as
defined  in the  Plan) of  the option  shares on  the date  of the  grant of the
option, or in the case of an ISO, one-hundred percent (100 percent) of the  fair
market  value of the option shares on the date of the option grant. The duration
of an option may not exceed ten years. Notwithstanding the foregoing, substitute
options  (defined  below)  will  have  exercise  prices,  terms  and  conditions
determined in accordance with the relevant option

                                       26
<PAGE>
agreements  and adjusted, where  applicable, for their  conversion to options on
Chiron Common  Stock,  and the  terms  of automatic  option  grants will  be  as
described under "Automatic Option Grants to Nonemployee Directors."

    Following stockholder approval of the 1991 Plan and upon consummation of the
mergers  between Chiron and  Cetus, Protos, and  Chiron Ophthalmics, outstanding
options under  those companies'  stock option  plans and  Chiron's prior  option
plans  (including related limited stock  appreciation rights) were converted, in
the manner and at  the exchange ratio specified  in the merger agreements,  into
options  to acquire Common Stock  under this Plan. On  the Effective Date of the
Plan, outstanding  automatic  option grants  under  the Chiron  1982  Plan  were
conformed,  other than to extend the term,  to the automatic option grants under
the Plan. Collectively, these options will be known as "substitute options."

    The exercise  price  is  generally  payable  in full  in  cash  or,  in  the
Committee's discretion, in Previously Owned Shares or, under certain conditions,
the  proceeds  of a  same day  sale  of the  award shares,  or  by means  of the
extension of secured or unsecured credit to the optionee.

    RESTRICTED SHARES, SHARE RIGHTS, AND SHARE UNITS

    Restricted shares, share rights and share units may be granted independently
of other compensation or in lieu of compensation that would otherwise be paid in
cash or stock options, whether at the election of the award holder or otherwise.
The number of restricted shares,  share rights or share  units to be awarded  in
lieu  of  any cash  compensation  amount or  number  of stock  options  shall be
determined by the Committee in its sole discretion and need not be equal to such
foregone compensation in fair market value. Restricted shares, share rights  and
share  units may be awarded  in tandem with stock options,  so that a portion of
such award becomes payable or  becomes free of restrictions  only if and to  the
extent  that the tandem options  are not exercised or  are forfeited, subject to
such terms and conditions  as the Committee may  specify. The terms,  conditions
and  restrictions to which restricted shares,  share rights, and share units are
subject will be determined in the sole discretion of the Committee, and may vary
from grant to grant. The Committee shall determine whether any consideration  is
to  be received by the  Company or its subsidiaries  as a condition precedent to
the issuance of restricted shares or shares issued pursuant to share rights.

    With respect  to  restricted shares  and  share rights,  the  Committee  may
provide  award holders  with an  election to receive  a percentage  of the total
value of the Company Stock subject to their restricted shares or share rights in
the form of a cash payment,  subject to such terms, conditions and  restrictions
as the Committee shall specify.

    A. Restricted Shares

    Restricted shares are shares of Company Stock, the retention and transfer of
which  is  subject  to terms  and  conditions (based  on  performance standards,
periods of service or  otherwise) determined by the  Committee. At the time  the
restricted  share  award is  made, the  Committee  will establish  a restriction
period applicable to such award. Generally, the award holder will have the right
to enjoy all  stockholder rights during  the restriction period,  except that  a
breach  of the terms and conditions established by the Committee pursuant to the
restricted share award will cause a  repurchase or forfeiture of the  restricted
share award.

    B. Share Rights

    A  share right consists of the right, subject to terms and conditions (based
on performance  standards, periods  of service  or otherwise)  as the  Committee
shall  establish, to receive shares  of Company Stock, and  if determined by the
Committee, cash dividend equivalents.

    C. Share Units

    A share unit consists of the right to receive an amount in cash equal to the
fair market value of one share of Company Stock on the date of valuation of  the
unit,  including, if  determined by the  Committee, a  cash dividend equivalent,
less such amount, if  any, as the Committee  shall specify. The Committee  shall
determine  the terms and conditions (based  on performance standards, periods of
service or otherwise), if any,  to which any such  payment will be subject.  The
award  holder  shall not  be entitled  to any  interest in  or to  any dividend,
voting, or other rights of a stockholder.

                                       27
<PAGE>
CORPORATE TRANSACTIONS

    In the event of an agreement to  dispose of all or substantially all of  the
assets  or outstanding capital stock of the  Company by means of a sale, merger,
reorganization, or  liquidation ("Corporate  Transaction"), each  award will  be
automatically  accelerated  so that  (1) options  become fully  exercisable with
respect to  the  total number  of  shares  purchasable under  the  options,  (2)
restrictions  on  restricted  shares will  be  eliminated, and  the  shares will
immediately vest, and (3) share rights and share units will immediately vest and
become payable. The Committee may also provide for the automatic termination  of
repurchase rights upon the occurrence of a Corporate Transaction.

    However,  the  terms and  conditions of  any outstanding  award will  not be
changed if the award is either assumed by the successor corporation, or replaced
with a comparable award by the successor corporation.

AUTOMATIC OPTION GRANTS TO NONEMPLOYEE DIRECTORS

    On the last business day  of the second quarter of  each fiscal year of  the
Company after December 10, 1991, each incumbent, continuing nonemployee director
will  receive an NSO to purchase 3,000 shares of Common Stock ("automatic option
grants") with an  option price  per share  equal to  the fair  market value  (as
defined in the Plan) of one share of Common Stock on that grant date, payable in
cash,  or  in shares  of Common  Stock held  at  least six  months, or  with the
proceeds of a  same day  sale of  the option shares.  Each person  who is  newly
elected  or appointed as  a nonemployee director after  December 10, 1991 (other
than on an automatic grant date) will  receive, on the date of such election  or
appointment,  an automatic option grant to purchase  a pro rata number of shares
of Common Stock. The pro  rata number will be  determined by multiplying 250  by
the  number  of  whole  calendar  months between  the  date  of  the nonemployee
director's election or appointment and the next automatic grant date.

    Each automatic option grant will have the following terms: (1) the  exercise
price  will be equal  to the fair market  value (as defined in  the Plan) of the
Common Stock on the date of grant, (2) the term of the option will be ten years,
(3) the  option  will expire  if  not exercised  within  ninety days  after  the
optionee  ceases  to serve  as  a director,  an  employee, a  consultant,  or an
independent contractor, or  within twelve  months after the  optionee ceases  to
provide  such services  due to  disability or  death, (4)  each automatic option
grant will be  exercisable at  any time for  all or  any part of  the number  of
granted  shares, and (5) the shares will be subject to repurchase by the Company
at the  original exercise  price if  a nonemployee  director ceases  to  provide
services  to Chiron or its subsidiaries as a director, an employee, a consultant
or an independent contractor. The Company's repurchase rights will lapse and the
optionee's  interest  in  the  purchased  shares  will  vest  in  equal   annual
installments  over  five years  from the  date of  grant, provided  the optionee
continues to provide  services to  the Company.  However, the  optionee will  be
immediately and fully vested upon death or disability.

    Nonemployee members of the Board who were newly elected or appointed between
July  1, 1990 and December 10, 1991 received  grants on that date for a pro rata
number of shares calculated as though the  grant were made on the date that  the
nonemployee  Board member was newly elected or  appointed and as though the date
that the nonemployee Board  member received an automatic  option grant (if  any)
under the Chiron 1982 Plan was an automatic grant date under this Plan.

ADJUSTMENTS

    Options,  restricted shares, share  rights, share units,  and any agreements
evidencing such awards shall be subject to adjustment by the Committee as to the
number and,  if applicable,  price of  shares of  stock or  other  consideration
obligation  subject to such  awards in the  event of changes  in the outstanding
stock due to a change in the  corporate or capital structure of the Company.  In
the  event of any such change in  the outstanding stock, the aggregate number of
shares available under the Plan may be appropriately adjusted by the  Committee,
whose determination shall be conclusive.

CANCELLATION AND REGRANT OF OPTIONS

    Under  the Plan, the Committee has the authority to effect at any time, with
the consent  of the  affected option  holders, the  cancellation of  any or  all
options  outstanding under  this Plan, the  prior Cetus Stock  Option Plans, the
Protos Corporation 1988  Stock Option  Plan, the Chiron  Ophthalmics, Inc.  1986
Stock

                                       28
<PAGE>
Option Plan, the 1982 Plan and the Non-Qualified Plan (the "Prior Plans") (other
than options granted under the automatic option grant provisions of these plans)
and  to grant  in substitution  therefor new options  for the  same or different
number of shares with an exercise price not less than 85 percent of fair  market
value  (as defined in  the Plan) on  the new grant  date or 100  percent of fair
market value if the new option is to be an ISO.

SURRENDER OF OPTIONS FOR CASH OR STOCK

    The Committee in its  discretion may implement  an option surrender  program
under  the Plan  through which one  or more  optionees may, under  the terms and
conditions established by the Committee, be  granted the right to surrender  all
or  part of an unexercised option for  an appreciation distribution equal to the
difference between the fair market value of the shares at the surrender date and
the option price  payable thereon. Such  distribution may be  made in shares  of
Company  Stock valued at fair market value on the date of surrender, in cash, or
partly in shares and partly in cash,  as the Committee, in its sole  discretion,
may  decide. The option surrender provisions are not applicable to the automatic
option grant provisions of the Plan.

REPURCHASE RIGHTS

    The Committee in  its discretion  may establish  as a  term of  one or  more
awards  granted  under the  Plan that  the  Company (or  its assigns)  will have
repurchase rights, exercisable upon the award holder's termination of employment
with, or  cessation of  services  for, the  Company  and its  subsidiaries.  The
Committee  will also have the authority to provide for the automatic termination
of the Company's repurchase  rights, in whole or  in part, thereby  accelerating
the  vesting of any or all of  the purchased shares (other than purchased shares
obtained pursuant to the  automatic option grant provisions  of this Plan)  upon
the occurrence of a Corporate Transaction.

RIGHT OF FIRST REFUSAL

    The  Committee in  its discretion  may establish  as a  term of  one or more
awards granted under the Plan that the Company has a right of first refusal with
respect to the  proposed disposition by  the award holder  (or any successor  in
interest by reason of purchase, gift or other mode of transfer) of any shares of
Company Stock acquired by the award holder. The instrument evidencing such right
of first refusal will specify the terms and conditions of that right.

SPECIAL CASH PAYMENTS RELATED TO CIBA-GEIGY TRANSACTION

    Pursuant  to one of the amendments that is the subject of this proposal, all
holders of options  to acquire shares  of Common  Stock under the  1991 Plan  on
November  20, 1994 were  granted certain cash payment  rights in connection with
the Ciba transaction.

    Each optionee was granted the right to receive a cash payment from Ciba with
respect to options outstanding on November  20, 1994 equal to (A) 37.33  percent
of  the number of shares of Common Stock  with respect to which each such option
would first  become exercisable  in calendar  year 1995  multiplied by  (B)  the
difference  between $117  per share  and the  exercise price  per share  of such
option with respect to such shares.  The portion of each option which  underlies
each  such  cash payment  is not  canceled  upon the  optionee's receipt  of the
payment from Ciba.

    With respect to the  remaining shares of Common  Stock subject to each  such
option  (i.e.,  those shares  with  respect to  which  the option  first becomes
exercisable before  or  after  1995),  each  optionee  was  granted  the  right,
exercisable  at any  time during  which such  option remains  outstanding and is
exercisable with  respect to  such shares,  to surrender  for cancellation  that
portion  of such option relating to 37.33 percent of such shares in return for a
cash payment from Ciba equal  to (A) the difference  between $117 per share  and
the  exercise price  per share of  such option  multiplied by (B)  the number of
shares with respect to which such option is so surrendered and canceled.

                                       29
<PAGE>
    However, the  grant and  exercise of  any  such right  with respect  to  any
executive  officer (i.e., an officer subject to  Section 16 of the Exchange Act)
or director of the  Company was approved by  the Compensation Committee and  was
made subject to stockholder approval of the grant of such right at the Company's
1995 stockholder meeting.

    The  grant of such rights, which are made with respect to 1,858,776 optioned
shares is in addition to, and does  not count against, the limits on the  number
of  shares with respect to which other awards  under the Plan may be made to all
individuals and/or a single individual. All  payments in respect of such  rights
are  to be made  by Ciba. The Company  has agreed that if  the payment under any
right would subject a  recipient to an excise  tax on excess parachute  payments
under  Section 4999 of  the Internal Revenue Code  ("Section 4999"), the Company
will make such  further cash payment  to the  recipient as may  be necessary  to
provide  the recipient with the same after-tax  amount that he or she would have
received in the absence of  such excise tax. The  Company does not believe  that
any  payments under  the rights  constitute excess  parachute payments. However,
because neither final regulations nor other definitive guidance has been  issued
under  Section  4999  relating to  the  type  of transaction  that  triggers the
application of that provision and the  type and value of rights that  constitute
excess  parachute payments, there  can be no assurance  that payments to certain
officers and one-percent stockholders of the Company will not constitute  excess
parachute payments.

NEW PLAN BENEFITS

    The  following tables  contain information  about (i)  stock options granted
under the Plan for  the Company's fiscal year  January 1, 1994 through  December
31,  1994, and  (ii) special  cash rights  granted in  connection with  the Ciba
transaction to the named executive officers and directors and groups indicated.

                  STOCK OPTIONS GRANTED UNDER THE PLAN IN 1994

<TABLE>
<CAPTION>
                                                                        NUMBER OF SHARES       AVERAGE EXERCISE
                                                                       SUBJECT TO OPTIONS           PRICE
                         NAME AND POSITION                                     (#)              OF OPTIONS ($)
- - --------------------------------------------------------------------  ---------------------  --------------------
<S>                                                                   <C>                    <C>
Edward E. Penhoet...................................................           35,000             $   78.125
  President and Chief Executive Officer
William J. Rutter...................................................           35,000                 78.125
  Chairman
William G. Green....................................................           10,000                 78.125
  Senior Vice President, Secretary and General Counsel
Dennis L. Winger....................................................           10,000                 78.125
  Senior Vice President, Finance & Administration, and
  Chief Financial Officer
David W. Martin.....................................................           30,000                 83.125
  Senior Vice President; President, Chiron Therapeutics
Current executive officers as a group (19 persons)..................          231,300                 72.524
Non-Executive Director Group (9 persons)............................           15,000                 55.500
All employees, including all current officers who are not executive
 officers, as a group (1683 employees)..............................          900,521                 70.442
</TABLE>

                                       30
<PAGE>
                   SPECIAL CASH RIGHTS GRANTED UNDER THE PLAN

<TABLE>
<CAPTION>
                                                                                   AGGREGATE          NUMBER
                                                                                 DOLLAR VALUE        OF RIGHTS
                              NAME AND POSITION                                     ($)(1)            (#)(2)
- - -----------------------------------------------------------------------------  -----------------  ---------------
<S>                                                                            <C>                <C>
Edward E. Penhoet............................................................    $   7,156,223           86,613
  President and Chief Executive Officer
William J. Rutter............................................................        9,312,818          107,146
  Chairman
William G. Green.............................................................        3,325,765           43,830
  Senior Vice President, Secretary and General Counsel
Dennis L. Winger.............................................................        3,762,567           45,522
  Senior Vice President, Finance & Administration, and Chief Financial
   Officer
David W. Martin..............................................................          379,434           11,201
  Senior Vice President; President, Chiron Therapeutics
Current executive officers as a group (19 persons)...........................       40,043,463          513,108
Non-Executive Director Group (9 persons).....................................        3,185,962           48,158
All employees, including current officers who are not
 executive officers, as a group (1683 persons)...............................       78,892,317        1,297,510
<FN>
- - ------------------------
(1)  Based upon difference between $117 per  share and exercise price of  option
     to which each right relates.
(2)  Of  the rights  in the  table granted to  the named  executive officers and
     directors and  groups indicated,  the  following number  of rights  at  the
     dollar  value  indicated applicable  to  options which  would  first become
     exercisable in  calendar  year  1995  do  not  require  that  the  optionee
     surrender  for cancellation the portion of each option underlying each such
     right: Edward E. Penhoet --  19,501 rights ($1,422,029); William J.  Rutter
     -- 19,501 rights ($1,422,029); William G. Green -- 8,687 rights ($611,812);
     Dennis  L.  Winger --  3,008 rights  ($146,819); David  W. Martin  -- 5,367
     rights ($181,807); current executive officers  as a group -- 95,602  rights
     ($6,026,338);  non-executive director group -- 8,325 rights ($500,383); all
     employees, including all current officers  who are not executive  officers,
     as a group -- 303,758 rights ($16,869,834).
</TABLE>

AMENDMENT OR TERMINATION

    The Board may amend, suspend or discontinue the Plan at any time. Generally,
the  provisions  of the  Plan  concerning automatic  option  grants may  only be
amended once  every six  months unless  necessary to  comply with  the  Internal
Revenue  Code. Without  stockholder approval, the  Board may  not (1) materially
modify the  requirements for  eligibility  and participation  in the  Plan,  (2)
materially  increase the number of shares which may be subject to awards granted
under the Plan (except  as provided above),  or (3) make  any other change  with
respect  to which the Board determines  that stockholder approval is required by
applicable law or regulatory standards.

    To the extent not  inconsistent with the Plan,  the Committee may modify  or
waive the terms of any outstanding award.

                                       31
<PAGE>
FEDERAL INCOME TAX CONSEQUENCES

    The  following  is  a  general description  of  certain  federal  income tax
consequences of the Plan. This description does not purport to be complete.

    The Company will be  entitled to a business  expense deduction equal to  the
ordinary  income recognized by an  optionee on exercise of  an NSO. The ordinary
income recognized will be equal  to the excess of the  fair market value of  the
purchased  shares on the date of recognition over the exercise price. Generally,
the date of recognition will be the  date the option is exercised or, if  later,
the first date shares acquired on exercise are not subject to a substantial risk
of forfeiture.

    The  Company will also be entitled to  a business expense deduction equal to
the  ordinary  income  recognized  by  an  optionee  due  to  a   "disqualifying
disposition"  of stock acquired pursuant to  an ISO. A disqualifying disposition
occurs if an optionee disposes  of the acquired shares  within two years of  the
date of the option grant, or within one year of the date the shares are acquired
by  the optionee. In the case of  a disqualifying disposition, the optionee will
generally recognize ordinary  income in the  year of disposition,  in an  amount
equal  to the amount of ordinary income  the optionee would have recognized from
the exercise of the option had the option been an NSO at the time of exercise.

    To the extent  that the aggregate  fair market value  (determined as of  the
respective  date or dates of grant) of shares with respect to which options that
would otherwise be  ISOs are exercisable  for the first  time by any  individual
during  any calendar  year exceeds  the sum  of $100,000,  such options  will be
treated as NSOs. To the extent that  an option may be surrendered for a  special
cash payment from Ciba, it will generally not qualify as an ISO.

    A  recipient of restricted shares  may be taxed in one  of two ways: (1) the
award holder  pays tax  when the  restrictions  lapse, or  (2) makes  a  special
election  to pay tax in the  year the grant is made.  The value of the award for
tax purposes is the fair market value of the shares at the applicable time, less
any consideration paid by the award holder  for the shares. This value is  taxed
as  ordinary income. When the award holder  is taxed, the Company receives a tax
deduction at the same time and for the same amount. If an award holder elects to
be taxed at grant,  when the restrictions  lapse, there will  be no further  tax
consequences  attributable to the awarded stock  until sale or other disposition
of the stock. However, dividends in cash and stock will be treated as follows:

        a.  if the above special tax election has been made, cash dividends paid
    to the award holder will be taxable dividend income to the award holder when
    paid, but the Company will not  be entitled to any corresponding  deduction;
    and

        b.   if  such election  has not  been made,  the award  holder will have
    taxable compensation income and the  Company a corresponding deduction  when
    the dividends are paid.

    A  recipient of  share rights  recognizes no taxable  income at  the time of
grant. However, when the conditions precedent to the issuance of shares pursuant
to such share rights  are satisfied, the award  holder would recognize  ordinary
income equal to the fair market value on the date of issuance of the shares less
any consideration paid by the award holder. Any cash dividend equivalent paid to
holders  of share rights is  ordinary income. The Company  will be entitled to a
deduction equal to the award holder's ordinary income recognized pursuant to the
issuance of shares under the award in the year recognized by the award holder.

    A recipient of  a share unit  recognizes no  taxable income at  the time  of
grant.  Whether a share unit  award is paid in cash  or shares of Company Stock,
the award  holder  will  have  ordinary  income and  the  Company  will  have  a
corresponding  deduction when the award is paid.  The measure of such income and
deduction will be the fair market value of the shares at the time of payment.

    If an award is accelerated as a result of a Corporate Transaction, all or  a
portion  of the value of the  award at that time may  be a parachute payment for
purposes of  the  Internal Revenue  Code's  excess parachute  provisions.  Those
provisions  generally provide that  if parachute payments  exceed three times an

                                       32
<PAGE>
award holder's  average  compensation  for  the five  tax  years  preceding  the
Corporate  Transaction, the  Company loses  its deduction  and the  recipient is
subject to a 20 percent excise tax  for the amount of the parachute payments  in
excess of such average compensation.

    A  special  cash payment  from Ciba  will constitute  taxable income  to the
recipient at the  time of  payment. The Company  believes that,  subject to  the
limits  of Section  162(m) of the  Internal Revenue Code  (applicable to certain
officers of the Company, as discussed below), the Company will be entitled to  a
deduction for the amount of each such payment.

DEDUCTION LIMIT FOR EXECUTIVE COMPENSATION

    Recently  enacted Section 162(m) of the Internal Revenue Code limits federal
income tax deductions for  compensation paid after 1993  to the chief  executive
officer  and the four other most highly compensated officers of a public company
to $1  million  per  year,  but  contains  an  exception  for  performance-based
compensation that satisfies certain conditions.

    The  Company believes that  stock options granted to  its executives with an
exercise price equal to or greater than the fair market value of Common Stock on
the date of grant will qualify for the performance based-compensation  exception
to  the  deduction  limit,  assuming  that  the  amended  Plan  is  approved  by
stockholders. However,  because final  regulations have  not been  issued  under
Section  162(m), there  can be  no assurance that  the options  will so qualify.
Based on proposed regulations and  commentary thereto, final regulations  issued
under  Section 162(m)  might require,  as a  condition to  continuing exemption,
certain changes to the composition of the Compensation Committee that may not be
acceptable to the Board of Directors, because they would exclude  representation
of  Ciba. If such regulations  do require such changes  and such changes are not
made, compensation paid  to named  executive officers under  such stock  options
would  generally cease to be exempt from the limitation of Section 162(m) on and
after the first  annual meeting  of stockholders at  which directors  are to  be
elected  that is held  on or after  January 1, 1996.  However, compensation paid
under stock  options that  were granted  on or  before February  17, 1993  would
continue to be exempt.

    The  cash payments to be  made by Ciba are  being specifically considered by
stockholders at the Annual Meeting (see  "Proposal 2: Approval of Amended  Stock
Option  Plan -- Special Cash Payments Related  to Ciba Transaction" at pp. 29-30
above), but, under proposed regulations issued by the Internal Revenue  Service,
will  not  be exempt  from application  of Section  162(m) even  if specifically
approved by the stockholders. As a result, if the amount of any such payment  to
any  of the five executive officers of  the Company subject to Section 162(m) in
any fiscal year, together with other  compensation paid to such officer in  such
fiscal  year that is not exempt from  the limitations of Section 162(m), exceeds
$1 million, the Company will  not be entitled to a  deduction for the amount  of
such excess.

VOTE REQUIRED FOR APPROVAL OF THE AMENDED CHIRON 1991 STOCK OPTION PLAN

    The  affirmative vote  of a  majority of the  shares of  Common Stock having
voting power present in person or represented by proxy, a quorum being  present,
is necessary to approve the amended Plan.

    THE  BOARD OF DIRECTORS RECOMMENDS  A VOTE FOR THE  PROPOSED AMENDED PLAN TO
LIMIT THE NUMBER OF SHARES  WITH RESPECT TO WHICH AWARDS  MAY BE MADE UNDER  THE
PLAN  TO  A SINGLE  INDIVIDUAL AND  TO  PROVIDE CERTAIN  CASH PAYMENT  RIGHTS IN
CONNECTION WITH THE CIBA TRANSACTION.

                                  PROPOSAL 3:
       APPROVAL OF 1995 EXECUTIVE OFFICER VARIABLE CASH COMPENSATION PLAN

    Chiron Corporation's 1995 Executive Officer Variable Cash Compensation  Plan
(the  "1995 Plan") was adopted  by the Board of  Directors on February 24, 1995,
subject to approval by the stockholders at the Annual Meeting. The 1995 Plan  as
adopted  by the  Board of Directors  was named the  Chiron Corporation Executive
Bonus Plan and was  later renamed. For the  officers eligible to participate  in
the  new  1995 Plan,  it  will supersede  the  discretionary variable  cash plan
previously   in    effect.    As    of   January    1,    1995,    approximately

                                       33
<PAGE>
19  officers are eligible  to be designated  to participate in  the 1995 Plan. A
copy of the new 1995  Plan is attached as Annex  2 to this Proxy Statement.  The
following  description of the 1995 Plan is a  summary and does not purport to be
fully descriptive. Reference is made to Annex 2 for more detailed information.

INTRODUCTION

    The 1995 Plan was established by the Company for the following purposes: (1)
to promote the interests of the  Company; (2) to provide incentives and  rewards
to  senior executives, as a group  and individually, who are largely responsible
for the management,  growth and profitability  of the Company  and (3) to  focus
incentives  upon  building value  for stockholders  by linking  senior executive
compensation to  the Company's  performance as  measured by  net income  or  the
market value of the Company's stock.

    Section  162(m) of the Internal  Revenue Code was signed  into law on August
10,  1993,  and  provides  that,  effective  January  1,  1994,  publicly  owned
corporations  like  the Company  may  not deduct  compensation  in excess  of $1
million per year paid to each of the Chief Executive Officer and the four  other
most highly paid executive officers unless the compensation is performance-based
and  paid under a stockholder-approved plan that satisfies certain conditions of
Section 162(m). The new 1995 Plan provides for the award of annual variable cash
compensation for each year through  1999 to the officers  of the Company at  the
level  of Vice-President and  above if one  or more performance  targets set for
each year is  met. The 1995  Plan is intended  to promote the  interests of  the
Company  by  providing  incentives  and rewards  to  its  most  senior executive
officers and by  qualifying such  compensation as  performance-based within  the
meaning  of Section 162(m). Because final regulations have not been issued under
Section 162(m), however, there can be  no assurance that such compensation  will
so  qualify. The 1995 Plan is administered  by the Compensation Committee of the
Board of Directors or  a subcommittee that currently  meets the requirements  of
Section  162(m) (the  "Committee"). However,  based on  proposed regulations and
commentary thereto, final regulations issued under Section 162(m) might require,
as a condition to  continuing exemption, certain changes  to the composition  of
the Compensation Committee that may not be acceptable to the Board of Directors,
because  they  would  exclude representation  of  Ciba. If  such  regulations do
require such changes and such changes  are not made, compensation paid to  named
executive  officers under the 1995 Plan would  generally cease to be exempt from
the limitation  of Section  162(m) on  and  after the  first annual  meeting  of
stockholders  at which  directors are  to be  elected that  is held  on or after
January 1, 1996.  The 1995 Plan  is not a  guarantee to any  participant of  any
bonus or continued employment.

ELIGIBILITY

    To  participate in the 1995 Plan, an officer  of the company at the level of
Vice-President or above must  be designated by name  or position as eligible  by
the Committee no later than March 31 during a year the 1995 Plan is in effect or
by  such  earlier date  as may  be  required by  Section 162(m).  Absent special
circumstances, no executive  may participate in  the 1995 Plan  for any year  in
which  he  or  she  terminates  employment  for  any  reason  other  than normal
retirement (after  attainment  of  age 65),  death,  disability  or  involuntary
termination without cause. In the event a participant's employment is terminated
for any of such reasons, the Committee may reduce or cancel the participation of
the  executive. No  executive subject  to the 1995  Plan may  participate in any
other Company incentive or bonus plan unless approved by the Committee.

DETERMINATION OF AWARDS UNDER 1995 PLAN

    For each fiscal year,  the Committee will establish  a cash target for  each
eligible  participant, either by  name or position,  which is payable  only if a
specified Company  performance  goal  is  satisfied  for  such  fiscal  year.  A
participant's  cash target for any fiscal year is a specified percentage (not to
exceed 150 percent) of that participant's  salary for the fiscal year.  However,
in  no event may a cash target  exceed $1 million. Both the specified percentage
and the Company performance  goal for a  fiscal year will  be determined by  the
Committee  within the first ninety (90) days  of such fiscal year of the Company
(or within such earlier period as shall be required under Section 162(m)).

    The performance goal of each fiscal year must be based on a specific measure
of Company performance based upon either stock price or earnings or both.  These
measures could include the achievement of a specified closing or average closing
price  of  Company common  stock,  the absolute  or  percentage increase  in the
closing or average closing  price of Company  common stock, one  or more of  the
following measures of the

                                       34
<PAGE>
Company's  net  income  for  such  fiscal  year  determined  in  accordance with
generally accepted accounting principles as consistently applied by the Company:
absolute net income or a percentage  or absolute dollar increase in net  income,
earnings  per share or a percentage or  absolute dollar increase in earnings per
share, or return on equity or a percentage or absolute dollar increase in return
on equity. The Committee may provide  for alternative levels of bonus  depending
on relative performance toward a performance goal. The Committee may establish a
goal based on one or more measures of stock price or net income or may establish
multiple  goals based on more than one measure, but any cash amount payable must
be based on the satisfaction of at least one goal.

    For purposes of the 1995  Plan, net income means  net income of the  Company
and  its consolidated subsidiaries  as reported by the  Company and certified by
its independent public accountants. However,  in fixing any goal, the  Committee
may exclude any or all of the following if they have a material effect on annual
net  income:  events  or  transactions  that are  either  unusual  in  nature or
infrequent  in   occurrence   (such   as   restructuring/organization   charges,
acquisitions  of businesses  or technologies,  the sale  or discontinuance  of a
business segment, the sale of investment securities, losses from litigation, the
cumulative effect of changes in  accounting principles, and natural  disasters),
depreciation, interest or taxes.

    Final  payouts are subject to the approval of the Committee and will be made
as soon as practical after  the close of the  Company's financial books for  the
fiscal year. The Committee has the right to reduce or cancel any payout based on
other   circumstances  relating  to  the  performance  of  the  Company  or  the
participant.

NEW PLAN BENEFITS

    Because the amount payable to an executive under the 1995 Plan is subject to
discretion as to the  target amount, the performance  goal selected and  whether
the  amount  resulting from  achievement  of such  goal  will actually  be paid,
neither the amount that will be paid in the future to any eligible executive nor
the amount that would have been paid last year had the 1995 Plan been in  effect
is presently determinable.

DEFERRAL

    All  or part of an award  made under the 1995 Plan  may be deferred with the
approval of the Committee. Any amounts deferred will accrue earnings based on  a
reasonable  rate of interest or on  one or more predetermined actual investments
(whether or not assets associated with  the amount originally owed are  actually
invested therein) such that the amount payable by the employer at the later date
will  be based on the actual rate  of return of a specific investment (including
any decrease as well  as any increase  in the value  of an investment).  Amounts
deferred  and earnings thereon will be distributed to the executive at such time
or times and in such manner as he  or she may specify, subject, however, to  any
restrictions  imposed by  the Committee.  Amounts deferred  and interest accrued
thereon are unfunded and unsecured obligations of the Company. A participant may
not assign, pledge  or otherwise encumber  his or her  interest in any  deferred
bonus  but  may  designate a  beneficiary  to receive  it  in the  event  of the
participant's death.

AMENDMENT AND TERMINATION

    The Company may amend, discontinue or terminate the 1995 Plan in whole or in
part at any time, except that any  amendment to the 1995 Plan that would  change
the  class of executives  eligible to receive awards,  the permissible amount of
such awards or any other amendment required to be made by the stockholders under
Section 162(m) must  receive stockholder  approval. No  awards may  be made  for
fiscal years beginning after 1999.

VOTE REQUIRED FOR APPROVAL OF NEW 1995 PLAN

    The  affirmative vote  of a  majority of the  shares of  Common Stock having
voting power present in person or represented by proxy, a quorum being  present,
is  necessary to approve the 1995 Plan. If  not approved, the 1995 Plan will not
be implemented.

    THE BOARD OF DIRECTORS RECOMMENDS A VOTE FOR APPROVAL OF THE 1995 PLAN.

                                       35
<PAGE>
                                  PROPOSAL 4:
                           RATIFICATION OF SELECTION
                       OF INDEPENDENT PUBLIC ACCOUNTANTS

    The Board  of Directors  has  selected KPMG  Peat  Marwick LLP  ("KPMG  Peat
Marwick")  to serve as independent public accountants for Chiron for the current
fiscal year. Ratification by the stockholders  will be sought for the  selection
by the Board of Directors of KPMG Peat Marwick as independent public accountants
to  audit the accounts and records of Chiron for the fiscal year ending December
31, 1995, and  to perform  other appropriate services.  Representatives of  KPMG
Peat  Marwick are  expected to be  present at  the Annual Meeting  to respond to
appropriate questions and to make a statement if the representatives so  desire.
In  the event that a majority  of the shares voting on  the matter at the Annual
Meeting does not vote  for ratification of the  selection of KPMG Peat  Marwick,
the  Board of Directors will reconsider such selection. Even if the selection is
ratified, the Board of Directors in its discretion may direct the appointment of
a different independent accounting firm at any time during the year if the Board
determines that such a change would be in the best interest of the Company.

    On March 7, 1994, the Finance and Audit Committee of the Company's Board  of
Directors,  by  delegated  authority of  the  Board of  Directors,  approved the
engagement of  the independent  certified public  accounting firm  of KPMG  Peat
Marwick  to audit the  consolidated financial statements of  the Company for the
year ended December 31, 1994. Accordingly,  the engagement of Ernst & Young  LLP
("Ernst  &  Young")  as  the  Company's  independent  auditors  was discontinued
effective upon conclusion of the  audit of the Company's consolidated  financial
statements  for the  year ended  December 31, 1993.  The audit  of the Company's
consolidated financial  statements for  the  year ended  December 31,  1993  was
completed on February 25, 1994.

    The  reports  of  Ernst  & Young  on  the  Company's  consolidated financial
statements for each of  the two fiscal  years in the  period ended December  31,
1993  did not contain an adverse opinion or a disclaimer of opinion and were not
qualified or modified as to uncertainty, audit scope or accounting principles.

    In connection  with  the  audits of  the  Company's  consolidated  financial
statements for each of the two fiscal years ended December 31, 1992 and 1993 and
the   subsequent  interim  period  prior  to   March  7,  1994,  there  were  no
disagreements between the Company and Ernst & Young on any matters of accounting
principles or practices, financial statement  disclosure, or auditing scope  and
procedures  which, if not resolved  to the satisfaction of  Ernst & Young, would
have caused Ernst & Young to make reference to the matter in their reports.

    There  were  no  reportable  events  (as  defined  in  Regulation  S-K  Item
304(a)(1)(v))  during the two fiscal years ended  December 31, 1992 and 1993 and
the subsequent interim period prior to March 7, 1994.

    The Company did not consult with KPMG Peat Marwick during the last two years
or subsequent interim period prior to March 7, 1994 on either the application of
accounting principles or type  of opinion KPMG Peat  Marwick might issue on  the
Company's financial statements.

    THE  BOARD OF DIRECTORS  RECOMMENDS A VOTE  FOR THE PROPOSAL  TO RATIFY KPMG
PEAT MARWICK AS  INDEPENDENT PUBLIC ACCOUNTANTS  OF THE COMPANY  FOR THE  FISCAL
YEAR ENDING DECEMBER 31, 1995.

    The  affirmative vote of the holders of a majority of the shares represented
and voting on the matter will be  required to ratify the selection of KPMG  Peat
Marwick.

                         COMPLIANCE WITH SECTION 16(A)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

    Section  16(a)  of  the Exchange  Act  requires the  Company's  officers and
directors, and persons who own more than 10 percent of a registered class of the
Company's equity  securities,  to  file  reports of  ownership  and  changes  in
ownership  on Forms  3, 4  and 5  with the  Securities and  Exchange Commission.
Officers, directors and  greater than  10 percent stockholders  are required  by
Securities and Exchange Commission regulation to furnish the Company with copies
of all Forms 3, 4 and 5 they file.

                                       36
<PAGE>
    Based  solely on  the Company's review  of the  copies of such  forms it has
received and written  representations from certain  reporting persons that  they
were  not required to  file Forms 5  for fiscal year  1994, the Company believes
that all  its  officers and  directors  complied with  all  filing  requirements
applicable  to them  with respect to  transactions during fiscal  year 1994. Mr.
Schuler filed late an amended Form 3 to reflect indirect ownership of 500 shares
of the  Company's stock  held by  his wife  in December  1991 when  he became  a
director.

                             STOCKHOLDER PROPOSALS

    Stockholder  proposals  intended  to  be  considered  for  inclusion  in the
Company's Proxy Statement for next year's Annual Meeting of Stockholders must be
received at the Company's principal executive office by December 10, 1995.  Such
proposals  may be included  in next year's  Proxy Statement if  they comply with
certain rules  and  regulations  promulgated  by  the  Securities  and  Exchange
Commission.

                                 OTHER BUSINESS

    The  Board  of  Directors is  not  aware of  any  other matter  that  may be
presented for action at the Annual Meeting. Should any other matter requiring  a
vote  of the stockholders arise, the enclosed  proxy card gives authority to the
persons listed on the card to vote  at their discretion in the best interest  of
the Company.

                     ANNUAL REPORT AND FINANCIAL STATEMENTS

    The   Company  has  chosen  again  this  year  to  print  summary  financial
information for  the fiscal  year ended  December 31,  1994 in  its 1994  Annual
Report,  a copy of which is enclosed  with this proxy material. The full audited
consolidated financial statements of the Company and its subsidiaries and  other
required  financial disclosures  appear in a  brochure enclosed  inside the back
cover of the Annual Report.

Dated: April 18, 1995                     BY ORDER OF THE BOARD OF DIRECTORS

                                          WILLIAM G. GREEN

                                          William G. Green,
                                            SECRETARY

                                       37
<PAGE>
                                                                         ANNEX 1

                         CHIRON 1991 STOCK OPTION PLAN
       [AS AMENDED AUGUST 14, 1993, APRIL 11, 1994 AND FEBRUARY 24, 1995]

I.  PURPOSES

    This  Chiron 1991  Stock Option Plan  ("Plan") is intended  to enable Chiron
Corporation ("Corporation") to attract and  retain the following individuals  by
offering them incentives and rewards, in the form of options, restricted shares,
share  rights, and share units ("awards") which will encourage them to acquire a
proprietary interest in the  Corporation and to continue  in the service of  the
Corporation   or  its  subsidiaries:  (a)   employees  (including  officers  and
directors) of the Corporation and its subsidiaries, (b) non-employee members  of
the  Board of  Directors of the  Corporation ("Board"), and  (c) consultants and
independent contractors who  perform valuable services  for the Corporation  and
its subsidiaries.

    In  addition, the Plan is intended to  permit the Corporation to satisfy its
obligations in connection with options it  will assume pursuant to the terms  of
the  Agreement and Plan  of Merger dated  as of July  21, 1991 by  and among the
Corporation,  Chiron  Acquisition  Subsidiary,   Inc.,  and  Cetus   Corporation
("Agreement").  Upon consummation of the transactions described in the Agreement
("Merger"), the Plan  will supersede  Cetus Corporation's  Amended and  Restated
Common  Stock Option Plan and  Cetus Corporation's Non-Employee Directors' Stock
Option Plan ("Cetus  Prior Plans").  Upon stockholder approval,  this Plan  will
also  supersede the  following Chiron prior  plans: the  Protos Corporation 1988
Stock  Option  Plan  (upon  the  merger  of  Protos  into  Chiron),  the  Chiron
Ophthalmics,  Inc. 1986 Stock Option Plan (upon the merger of Chiron Ophthalmics
into a wholly owned subsidiary of  Chiron), the Corporation's 1982 Stock  Option
Plan  and the Corporation's 1984  Non-Qualified Stock Option Plan (collectively,
"Chiron Prior Plans").

II.  ADMINISTRATION

    The Plan will be administered by a committee or committees appointed by  the
Board and consisting of one or more members of the Board. The Board may delegate
the  responsibility for  administration of the  Plan with  respect to designated
classes of award holders to different committees, subject to such limitations as
the Board deems appropriate. With respect  to any matter, the term  "Committee,"
when  used in  this Plan, will  refer to  the committee that  has been delegated
authority with respect  to such matter.  Members of a  committee will serve  for
such  term as  the Board may  determine, and will  be subject to  removal by the
Board at any time.

    (a)  16(B).  The composition of any committee responsible for administration
of the  Plan with  respect  to award  holders who  are  subject to  the  trading
restrictions  of Section  16(b) of  the Securities  Exchange Act  of 1934 ("1934
Act") with  respect  to securities  of  the  Corporation will  comply  with  the
applicable requirements of Rule 16b-3 of the Securities and Exchange Commission.

    (b)    AUTHORITY.   Any  committee appointed  by  the Board  will  have full
authority  to  administer   the  Plan   within  the  scope   of  its   delegated
responsibilities,  including authority  to interpret  and construe  any relevant
provision of  the Plan,  to adopt  such rules  and regulations  as it  may  deem
necessary,  and to determine the  terms and conditions of  awards made under the
Plan (which need  not be identical).  Decisions of a  committee made within  the
discretion delegated to it by the Board will be final and binding on all persons
who have an interest in the Plan.

III.  ELIGIBILITY FOR AWARDS

    (a)   DISCRETIONARY  AWARDS.  From  time to  time the Committee  may, in its
discretion, select individuals  from among the  following categories to  receive
awards under the Plan:

        (1)   EMPLOYEES.  The Committee  may select employees of the Corporation
    or its  subsidiaries  (including officers,  whether  or not  they  are  also
    members of the Board).

                                      A-1
<PAGE>
        (2)   CONSULTANTS AND INDEPENDENT CONTRACTORS.  The Committee may select
    consultants and independent  contractors whose services  tend to  contribute
    materially  to the success  of the Corporation or  its subsidiaries or whose
    services may reasonably be anticipated to so contribute.

    (b)  AUTOMATIC GRANTS.   Members of the Board who  are not employees of  the
Corporation  or its  subsidiaries will receive  options in  accordance with, and
only in accordance with, the Plan's automatic grant provisions.

    (c)   SUBSTITUTE OPTIONS.    Upon consummation  of the  Merger,  outstanding
options   under  the  Cetus   Prior  Plans  (including   related  Limited  Stock
Appreciation Rights) will be converted, in the manner and at the exchange  ratio
specified  in the Agreement, into substitute  options under this Plan to acquire
Common Stock (as defined below). Upon  stockholder approval and, with regard  to
the  Protos prior  plan options and  the Chiron Ophthalmics  prior plan options,
consummation of the relevant mergers, outstanding options under the Chiron Prior
Plans will  be  converted into  options  under  this Plan.  These  options  will
preserve  the exercise price of the outstanding options as adjusted, in the case
of options under the  Protos Corporation 1988 Stock  Option Plan and the  Chiron
Ophthalmics,  Inc. 1986 Stock Option Plan, to reflect the substitution of Common
Stock. These options will  also preserve the other  terms and conditions of  the
outstanding options; provided, however, that on the Effective Date of this Plan,
outstanding  automatic option grants  under the Corporation's  1982 Stock Option
Plan will be conformed, other than to  extend the term, to the Automatic  Option
Grants under this Plan. Collectively, these options will be known as "Substitute
Options."

IV.  STOCK SUBJECT TO THE PLAN

    (a)    CLASS.   The  stock  subject to  awards  under  the Plan  is  (i) the
Corporation's authorized  but  unissued  or  reacquired  Common  Stock  ("Common
Stock"),  or (ii) shares of  one or more series  of the Corporation's authorized
but unissued or reacquired Restricted  Common Stock, in the aggregate,  "Company
Stock."  In connection with the grant of  awards under the Plan, the Corporation
may repurchase shares in the open market or otherwise.

    (b)  AGGREGATE AMOUNT

        (1)  SHARES.  Subject to  adjustment under Sections IV(c) and  IV(b)(3),
    the  aggregate maximum number of shares of Company Stock that may be subject
    to awards under the Plan is 4,500,000  plus the number of shares of  Company
    Stock  remaining for issuance on  the Effective Date of  this Plan under the
    Corporation's  1982   Stock  Option   Plan   and  the   Corporation's   1984
    Non-Qualified  Stock  Option  Plan.  Notwithstanding  the  foregoing,  as of
    January 1 of each fiscal year after 1991, the aggregate number of shares  of
    Company Stock that may be subject to awards under the Plan will be increased
    by  1.50% of the number of Chiron Common Equivalent Shares outstanding as of
    December 31 of the  preceding fiscal year. The  maximum number of shares  of
    Company  Stock with respect to which options  may be granted to any employee
    during the term of the Plan is 1,000,000 shares. Subject to adjustment under
    Sections IV(c) and IV(b)(3), not more than 4,500,000 shares of Company Stock
    plus the number  of shares of  Company Stock remaining  for issuance on  the
    Effective  Date of this Plan under  the Corporation's 1982 Stock Option Plan
    and the Corporation's 1984 Non-Qualified Stock Option Plan may be subject to
    Incentive Options  (as  defined below)  granted  under the  Plan  after  the
    Effective  Date. "Chiron Common  Equivalent Shares" are  the total number of
    outstanding shares of Common Stock plus the total number of shares of Common
    Stock issuable upon conversion or exercise of outstanding warrants,  options
    and  convertible securities.  In no event  will more than  500,000 shares of
    Restricted Common Stock, whether in a  single series or in multiple  series,
    be subject to award under the Plan.

        (2)   RESTRICTED COMMON STOCK.  Shares of Restricted Common Stock may be
    issued  under  the  Plan  in  one  or  more  separate  series.  The  rights,
    preferences  and privileges, together with  the restrictions and limitations
    and the number of shares, of each series of Restricted Common Stock issuable
    under the  Plan  will be  set  forth  in the  Corporation's  Certificate  of
    Determination  of Preferences of  Common Stock ("Certificate")  as in effect
    from time to  time during the  term of the  Plan. Shares of  each series  of
    Restricted  Common Stock will be convertible  or exchangeable into shares of
    Common Stock in accordance with the terms and provisions of the  Certificate
    applicable to that series.

                                      A-2
<PAGE>
        (3)   REUSE OF SHARES.  If any outstanding option under the Chiron Prior
    Plans, the Cetus Prior Plans or this Plan (including the Substitute Options)
    expires or is terminated or cancelled for any reason (including pursuant  to
    Section X of the Plan but other than pursuant to surrender of the option for
    a  cash payment in  accordance with Section  XIII of the  Plan) before being
    exercised for the full number of shares to which it applies, then the shares
    allocable to the  unexercised portion  of such  option will  not be  charged
    against  the limitations of  Section IV(b)(1) and  will become available for
    subsequent grants under the Plan. To the extent that a share right or  share
    unit  expires or is terminated,  or is canceled or  forfeited for any reason
    without being paid in cash or shares of Company Stock, any remaining  shares
    allocable  to the unpaid portion of such share right or share unit shall not
    be charged  against the  limitations  of Section  IV(b)(1) and  will  become
    available  again for subsequent grants under the Plan. Shares subject to any
    option or portion of an option surrendered in accordance with the "Surrender
    of Options for Cash or  Stock" provisions of this  Plan, shares for which  a
    cash payment is made in lieu thereof under a restricted share, share unit or
    share  right,  and shares  forfeited to  or  repurchased by  the Corporation
    pursuant to its forfeiture and repurchase rights under this Plan will not be
    available for subsequent awards under the Plan.

    (c)  ADJUSTMENTS.   In the  event any change  is made to  the Company  Stock
subject to the Plan (whether by reason of merger, consolidation, reorganization,
recapitalization,  stock dividend, stock split,  combination of shares, exchange
of shares, or other change in corporate or capital structure of the Corporation)
then, unless such change results in the termination of all awards, the Committee
will make  appropriate adjustments  to the  kind and  maximum number  of  shares
subject to the Plan, the kind and maximum number of shares for which options are
to  be granted to non-employee directors, and the kind and number of shares and,
where applicable, price per share of stock subject to outstanding awards.

V.  TERMS AND CONDITIONS OF OPTIONS

    Stock options granted under the Plan may, in the Committee's discretion,  be
either  incentive stock  options ("Incentive Options")  qualifying under Section
422 of the Internal Revenue Code of 1986, as amended ("Internal Revenue  Code"),
or nonstatutory options. Individuals who are not employees of the Corporation or
its  subsidiaries  may only  be granted  nonstatutory  options. Options  will be
evidenced by instruments in  such form as  the Committee may  from time to  time
approve.  These instruments will  conform to the  following terms and conditions
and, in  the  discretion  of  the  Committee,  may  contain  such  other  terms,
conditions and restrictions as are not inconsistent with the following:

    (a)    OPTION PRICE.    The option  price  per share  will  be fixed  by the
Committee, but  in  no event  will  the option  price  per share  be  less  than
eighty-five  percent (85%) of the Fair Market  Value of the option shares on the
date of the option grant;  provided, however, that in  no event will the  option
price  per share of an Incentive Option  be less than one-hundred percent (100%)
of the Fair Market Value of the option  shares on the date of the option  grant.
Notwithstanding  the foregoing, Substitute Options will have an option price per
share determined pursuant to Section III(c)  of this Plan and interim  Automatic
Option Grants will have an option price per share determined pursuant to Section
VII(a)(3) of the Plan.

    (b)  NUMBER OF SHARES, TERM AND EXERCISE

        (1)    TERM AND  NUMBER.   Each option  granted under  the Plan  will be
    exercisable on such date or dates,  during such period, and for such  number
    of shares of Company Stock as the Committee determines and sets forth in the
    instrument evidencing the option. No option granted under the Plan will have
    an  expiration date that is more than 10  years after the date of the option
    grant.

        (2)   EXERCISE.    After  any option  granted  under  the  Plan  becomes
    exercisable,  it may be exercised  by notice to the  Corporation at any time
    prior to  the  termination of  such  option.  Except as  authorized  by  the
    Committee  in accordance with Section VIII,  the option price for the number
    of shares for which the option is exercised will become due and payable upon
    exercise.

                                      A-3
<PAGE>
        (3)   PAYMENT.   The  option  price will  be  payable in  full  in  cash
    (including  cash equivalents);  provided, however,  that the  Committee may,
    either at the time the option is granted or at the time it is exercised  and
    subject to such limitations as it may determine, authorize payment of all or
    a  portion of  the option  price in  one or  a combination  of the following
    alternative forms:

           (i) a promissory note authorized pursuant to Section VIII;

           (ii) full payment in shares of Common Stock valued as of the exercise
       date and  held  for  the  requisite  period to  avoid  a  charge  to  the
       Corporation's earnings; or

          (iii) by delivery of a properly executed exercise notice together with
       irrevocable   instructions  to  a  broker  to  promptly  deliver  to  the
       Corporation the amount of sale or loan proceeds to pay the option price.

    (c)  TERMINATION OF SERVICES.  The Committee will determine and set forth in
each option whether the  option will continue to  be exercisable, and the  terms
and  conditions of such exercise, on and  after the date that an optionee ceases
to  be  employed  by,  or  to  provide  services  to,  the  Corporation  or  its
subsidiaries.  The date of  termination of an  optionee's employment or services
will be determined by the Committee, which determination will be final.

    (d)  INCENTIVE OPTIONS.  Options granted under the Plan that are intended to
be Incentive  Options will  be subject  to the  following additional  terms  and
conditions:

        (1)   DOLLAR LIMITATION.   To the extent that  the aggregate Fair Market
    Value (determined as  of the respective  date or dates  of grant) of  shares
    with  respect to which  options that are  granted after 1986  and that would
    otherwise be Incentive  Options are exercisable  for the first  time by  any
    individual during any calendar year under the Plan (or any other plan of the
    Corporation,  a  parent or  subsidiary  corporation or  predecessor thereof)
    exceeds the sum  of $100,000  (or such greater  amount as  may be  permitted
    under  the  Internal Revenue  Code), whether  by  reason of  acceleration or
    otherwise, such options will not be treated as Incentive Options. In  making
    such  a determination, options  will be taken  into account in  the order in
    which they  were  granted.  The  aggregate fair  market  value  (as  of  the
    respective  date or dates of  grant) of shares of  the Company (or parent or
    subsidiary corporation) for which Incentive Options could be granted to  any
    one  individual  in a  single  calendar year  before  1987 could  not exceed
    $100,000 at the time of grant,  plus unused carryovers from the  immediately
    preceding three calendar years.

        (2)  10% STOCKHOLDER.  If any employee to whom an Incentive Option is to
    be  granted pursuant to the provisions of the Plan is, on the date of grant,
    the owner of stock (determined with application of the ownership attribution
    rules of Section 424(d) of the  Internal Revenue Code) possessing more  than
    ten percent (10%) of the total combined voting power of all classes of stock
    of  his  or  her  employer  corporation  or  of  its  parent  or  subsidiary
    corporation ("10% Stockholder"), then the following special provisions  will
    apply to the option granted to such individual:

           (i) The option price per share of the stock subject to such Incentive
       Option  will not be less than one  hundred ten percent (110%) of the Fair
       Market Value of the option shares on the date of grant; and

           (ii) The option will not have a term in excess of five (5) years from
       the date of grant.

        (3)  SEQUENTIAL EXERCISE.  No Incentive Option granted before January 1,
    1987 may be exercised  while there remains  outstanding any other  Incentive
    Option  to  purchase shares  of  the Company  (or  its parent  or subsidiary
    corporation) which was granted at an earlier date to the optionee.

        (4)  PARENT AND SUBSIDIARY.   For purposes of this Section V(d)  "parent
    corporation"  and "subsidiary corporation" will  have the meaning attributed
    to those terms, as they are used  in Section 422(b) of the Internal  Revenue
    Code.

                                      A-4
<PAGE>
    (e)  WITHHOLDING

        (1)    OBLIGATION.    The  Corporation's  obligation  to  deliver  stock
    certificates upon the exercise  of an option will  be subject to the  option
    holder's  satisfaction of all applicable federal, state and local income and
    employment tax withholding requirements.

        (2)  PAYMENT.  In the event that an option holder is required to pay  to
    the  Corporation  an  amount  with  respect  to  income  and  employment tax
    withholding obligations  in  connection  with exercise  of  an  option,  the
    Committee  may, in its discretion and  subject to such limitations and rules
    as it may  adopt, permit  the option holder  to satisfy  the obligation,  in
    whole  or in part, by delivering shares  of Common Stock already held by the
    option holder or  by making an  irrevocable election that  a portion of  the
    total  value of the shares subject to the option be paid in the form of cash
    in lieu of  the issuance of  Company Stock,  and that such  cash payment  be
    applied to the satisfaction of the withholding obligations.

VI.  RESTRICTED SHARES, SHARE RIGHTS AND SHARE UNITS

    (a)  NATURE OF AWARDS

        (1)  RESTRICTED SHARES.  A restricted share granted under the Plan shall
    consist  of shares of Company Stock, the  retention and transfer of which is
    subject to  such  terms,  conditions  and  restrictions  (whether  based  on
    performance  standards  or periods  of  service or  otherwise  and including
    repurchase and/or  forfeiture rights  in favor  of the  Corporation) as  the
    Committee  shall determine. The terms,  conditions and restrictions to which
    restricted shares are subject shall be evidenced by instruments in such form
    as the Committee may from  time to time approve and  may vary from grant  to
    grant. The Committee shall have the absolute discretion to determine whether
    any consideration (other than the services of the potential award holder) is
    to  be  received  by the  Corporation  or  its subsidiaries  as  a condition
    precedent to the issuance of restricted shares.

        (2)  SHARE RIGHTS.  A share  right granted under the Plan shall  consist
    of  the right, subject  to such terms,  conditions and restrictions (whether
    based on  performance standards  or  periods of  service or  otherwise),  to
    receive a share of Company Stock (together with cash dividend equivalents if
    so  determined by the Committee) as  the Committee shall determine and shall
    be evidenced by instruments in such form  as the Committee may from time  to
    time  approve. The Committee shall have the absolute discretion to determine
    whether any consideration (other  than the services  of the potential  award
    holder)  is  to be  received by  the  Corporation or  its subsidiaries  as a
    condition precedent to the issuance of shares pursuant to share rights.  The
    terms,  conditions and  restrictions to which  share rights  are subject may
    vary from grant to grant.

        (3)  SHARE UNITS.  A share unit granted under the Plan shall consist  of
    the right to receive an amount in cash equal to the fair market value of one
    share  of Company Stock on the date  of valuation of the unit (together with
    cash dividend  equivalents if  so  determined by  the Committee)  less  such
    amount,  if any, as the  Committee shall specify. The  date of valuation and
    payment of cash under a share unit and the conditions, if any, to which such
    payment will be subject (whether  based on performance standards or  periods
    of  service or otherwise)  shall be determined by  the Committee. The terms,
    conditions and restrictions to which share  units are subject may vary  from
    grant to grant.

    (b)   WITHHOLDING.  The Committee may  require, or permit an award holder to
elect, that a portion of the total  value of the shares of Common Stock  subject
to  restricted shares or share rights held by  one or more award holders be paid
in the form of cash in lieu of the issuance of Company Stock and that such  cash
payment  be applied to the  satisfaction of the federal,  state and local income
and employment tax withholding obligations that arise at the time the restricted
shares and share rights become free of all restrictions under the Plan.

    (c)   CASH  PAYMENTS.   The  Committee may  provide  award holders  with  an
election to receive a percentage of the total value of the Company Stock subject
to  restricted shares or share rights in the  form of a cash payment, subject to
such terms, conditions and restrictions as the Committee shall specify.

                                      A-5
<PAGE>
    (d)  ELECTIVE AND TANDEM AWARDS.  The Committee may award restricted shares,
share rights and share units independently  of other compensation or in lieu  of
compensation  that would otherwise be paid in  cash or stock options, whether at
the election  of  the  potential  award  holder  or  otherwise.  The  number  of
restricted shares, share rights or share units to be awarded in lieu of any cash
compensation  amount  or number  of  stock options  shall  be determined  by the
Committee in  its  sole  discretion and  need  not  be equal  to  such  foregone
compensation  in fair market value. In addition, restricted shares, share rights
and share units may be awarded in  tandem with stock options, so that a  portion
of such award becomes payable or becomes free of restrictions only if and to the
extent  that the tandem options  are not exercised or  are forfeited, subject to
such terms and conditions as the Committee may specify.

    (e)  MODIFICATION  OF AWARDS.   The Committee may,  in its sole  discretion,
modify  or waive any or all of  the terms, conditions or restrictions applicable
to any  outstanding  restricted share,  share  right or  share  unit;  provided,
however,  that no such modification or waiver  shall, without the consent of the
holder of an outstanding award, adversely affect the holder's rights thereunder.

VII.  AUTOMATIC OPTION GRANTS TO DIRECTORS

    (a)   GRANTS.   Non-employee  members of  the  Board will  automatically  be
granted  nonstatutory options ("Automatic Option Grants") to purchase the number
of shares of Common Stock set  forth below (subject to adjustment under  Section
IV(c) hereof) on the dates and terms set forth below:

        (1)   CONTINUING  DIRECTORS.   On the  last business  day of  the second
    quarter of each fiscal year of  the Corporation after the Effective Date  of
    this  Plan ("Automatic Grant Date"),  each continuing non-employee member of
    the Board will receive an Automatic Option Grant to purchase 3,000 shares of
    Common Stock.

        (2)  NEW DIRECTORS.  Each person who is newly elected or appointed as  a
    non-employee  member  of the  Board after  the Effective  Date of  this Plan
    (other than on an Automatic  Grant Date) will receive,  on the date of  such
    election  or appointment, an  Automatic Option Grant to  purchase a pro rata
    number of shares of Common Stock. The pro rata number will be determined  by
    multiplying  250 by the number of whole  calendar months between the date of
    the non-employee director's election or  appointment and the next  Automatic
    Grant Date.

        (3)   INTERIM GRANTS.  Non-employee members  of the Board who were newly
    elected or appointed  between July 1,  1990 and the  Effective Date of  this
    Plan received grants under this Section VII(a) on the Effective Date of this
    Plan  for a pro  rata number of  shares calculated as  though the grant were
    made on the date that the non-employee member of the Board was newly elected
    or appointed ("Interim Grants"). The  terms and conditions of these  Interim
    Grants  will be  determined under Section  VII(b) below, as  though the date
    that the non-employee member was elected or appointed was the grant date and
    as though the  date that the  non-employee member of  the Board received  an
    automatic  grant (if any) under the Corporation's 1982 Stock Option Plan was
    an Automatic Grant Date under this Plan.

        (4)   ADVISORY COUNSELLORS.    Advisory Counsellors  of Cetus  will  not
    qualify for Automatic Option Grants.

    (b)   TERMS  AND CONDITIONS.   The terms  and conditions  applicable to each
Automatic Option Grant will be as follows:

        (1)  PRICE.   The option price  per share will be  equal to one  hundred
    percent  (100%) of the Fair Market Value of one share of Common Stock on the
    date of grant;

        (2)  TERM.  The options will have terms of (10) years, measured from the
    date of grant, and will be exercisable at any time during their term for all
    or any part of the covered shares; provided, however, that no options may be
    exercised prior to approval of the Plan by the Corporation's stockholders.

        (3)  REPURCHASE.  The shares purchased under the options will be subject
    to repurchase by the Corporation at the original exercise price in the event
    an  optionee  ceases  to  provide   services  to  the  Corporation  or   its
    subsidiaries  as a  director, an  employee, a  consultant or  an independent
    contractor.

                                      A-6
<PAGE>
    The Corporation's repurchase rights will lapse, and the optionee's  interest
    in  the purchased shares will vest, in a series of equal annual installments
    over the five-year  period measured  from the  date of  grant; provided  the
    optionee  continues to provide such services. In addition, the Corporation's
    repurchase right will lapse  in its entirety, and  full vesting will  occur,
    should  one or  more of  the following  events occur  while the  optionee is
    providing such services:  (A) the  optionee's death, or  (B) the  optionee's
    permanent disability.

        (4)   PAYMENT.   Upon exercise of  the option, the  option price for the
    purchased shares will  become payable immediately  in cash or  in shares  of
    Common Stock that the optionee has held for at least six (6) months. Payment
    may also be made by delivery of a properly executed exercise notice together
    with  irrevocable  instructions  to  a broker  to  promptly  deliver  to the
    Corporation the amount of sale or loan proceeds to pay the option price.

        (5)  CESSATION.  In the event the optionee ceases to provide services to
    the Corporation or its subsidiaries as a director, an employee, a consultant
    or an independent contractor, the option  may be exercised, within the  term
    of  the option,  for a  period of three  (3) months  after the  date of such
    cessation (twelve  (12)  months  in  the case  of  cessation  by  reason  of
    disability  or death).  In the  case of death,  the option  may be exercised
    within such period by the estate or heirs of the optionee.

VIII.  LOANS AND INSTALLMENT PAYMENTS

    In order to assist an award holder (including an employee who is an  officer
or  director of the Corporation)  in the acquisition of  shares of Company Stock
pursuant to  an  award  granted under  the  Plan  (other than  pursuant  to  the
Automatic Option Grant provisions of this Plan), the Committee may authorize, at
either  the time  of the grant  of an  award or the  time of  the acquisition of
Company Stock pursuant to  the award (i)  the extension of a  loan to the  award
holder  by the Corporation, (ii) the payment by the award holder of the purchase
price, if any, of the Company Stock  in installments, or (iii) the guarantee  by
the  Corporation of a loan obtained by the  award holder from a third party. The
terms of any loans, guarantees  or installment payments, including the  interest
rate and terms of repayment, will be subject to the discretion of the Committee.
Loans,  installment payments and guarantees may be granted without security, the
maximum credit available being the purchase price, if any, of the Company  Stock
acquired  plus the maximum federal and state income and employment tax liability
that may be incurred in connection with the acquisition.

IX.  ASSIGNABILITY

    No award granted under the Plan  is assignable or transferable by the  award
holder other than by Will or by the laws of descent and distribution, and during
the  lifetime of the award holder, only the award holder may exercise options or
exercise the rights provided under awards granted under the Plan.

X.  CANCELLATION AND NEW GRANT OF OPTIONS

    The Committee will have the authority to  effect, at any time and from  time
to  time, with the consent  of the affected option  holders, the cancellation of
any or all outstanding options  under the Plan, a Cetus  Prior Plan or a  Chiron
Prior  Plan (other than options granted  under automatic option grant provisions
of these plans) and to grant in substitution therefor new options under the Plan
covering the same or different numbers of shares, but having an option price per
share not less than eighty-five  percent (85%) of the  Fair Market Value on  the
new  grant date  or, in  the case  of an  Incentive Option,  one hundred percent
(100%) of the Fair  Market Value on the  new grant date (or,  in the case of  an
Incentive Option granted to a 10% Stockholder, one hundred ten percent (110%) of
such Fair Market Value). If one or more of the cancelled options is an Incentive
Option granted before 1987 under a Cetus Prior Plan or a Chiron Prior Plan, then
such  option  will,  solely  for  purposes  of  the  "sequential  exercise" rule
applicable to outstanding Incentive Options  granted before 1987, be  considered
to  be outstanding until the expiration  date initially specified for the option
term of such option.

XI.  ACCELERATION AND TERMINATION OF AWARDS

    (a)   ACCELERATION.   In the  event of  an agreement  to dispose  of all  or
substantially  all of the assets or outstanding capital stock of the Corporation
by means of a sale, merger,  reorganization, or liquidation, each award will  be
automatically  accelerated  so that  (1) options  become fully  exercisable with
respect to the total

                                      A-7
<PAGE>
number of  shares purchasable  under the  options, provided,  however, that  the
exercise  of accelerated  Incentive Options  granted prior  to 1987  will remain
subject to any  limitations imposed  by the Internal  Revenue Code's  sequential
exercise rule, (2) restrictions on restricted shares will be eliminated, and the
shares  will  immediately  vest,  and  (3) share  rights  and  share  units will
immediately vest and  become payable.  The Committee  may also  provide for  the
automatic termination of repurchase rights upon the occurrence of such an event.

    (b)   NO ACCELERATION.  No acceleration of awards will occur if the terms of
the agreement require as  a prerequisite to the  consummation of any such  sale,
merger,  reorganization  or  liquidation that  each  such award  will  be either
assumed by the  successor corporation or  parent thereof or  be replaced with  a
comparable  award  subject  to shares  of  the successor  corporation  or parent
thereof. The determination of such comparability will be made by the  Committee,
and  its determination will be final,  binding and conclusive. Upon consummation
of  the  sale,  merger,  reorganization  or  liquidation  contemplated  by   the
agreement, all awards, whether or not accelerated, will terminate unless assumed
pursuant to a written agreement by the successor corporation or parent thereof.

    (c)   CORPORATE STRUCTURE.   The grant of awards under  this Plan will in no
way affect the right  of the Corporation to  adjust, reclassify, reorganize,  or
otherwise  change its  capital or business  structure or  to merge, consolidate,
dissolve, liquidate or  sell or  transfer all  or any  part of  its business  or
assets.

XII.  VALUATION

    With  regard to all Substitute Options, Fair Market Value will be determined
in accordance  with the  relevant option  plan documents  on the  date that  the
outstanding options were granted. With regard to awards granted under this Plan,
for  all valuation purposes under the Plan, the  Fair Market Value of a share of
Common Stock or Restricted  Common Stock (as  the case may  be) on any  relevant
date will be determined in accordance with the following provisions:

    (a) If the Common Stock or Restricted Common Stock is not at the time listed
or   admitted  to  trading  on  any  stock   exchange,  but  is  traded  in  the
over-the-counter market, the Fair Market Value  will be the average between  the
reported  high price and the reported low price  of one share of Common Stock or
Restricted Common Stock  (as the case  may be) on  the date in  question in  the
over-the-counter market, as such prices are reported by the National Association
of Securities Dealers through its NASDAQ system or any successor system.

    (b)  If the Common Stock or Restricted Common Stock is at the time listed or
admitted to trading on any  stock exchange, then the  Fair Market Value will  be
the  average between the reported  high price and the  reported low price of one
share of Common Stock  or Restricted Common  Stock (as the case  may be) on  the
date in question on the stock exchange that is the primary market for the stock,
as such prices are officially quoted on such exchange.

    (c)  If the Common Stock or Restricted Common  Stock (as the case may be) is
at the time neither  listed nor admitted  to trading on  any stock exchange  nor
traded  in  the over-the-counter  market, or  if  the Committee  determines that
neither subparagraph (a) nor subparagraph  (b) above reflects Fair Market  Value
of  the stock  and the award  was not  granted pursuant to  the Plan's Automatic
Option Grant provisions, then  the Fair Market Value  will be determined by  the
Committee  after  taking  into  account  such  factors  as  the  Committee deems
appropriate, or in the case of Automatic Option Grants, by an independent  third
party valuation.

XIII.  SURRENDER OF OPTIONS FOR CASH OR STOCK

    (a)   STOCK  APPRECIATION RIGHTS.   If,  and only  if the  Committee, in its
discretion, elects to implement an option surrender program under the Plan,  one
or  more option holders may, upon such terms and conditions as the Committee may
establish at the time of the option grant or at any time thereafter, be  granted
the  right to surrender all  or part of an unexercised  option in exchange for a
distribution equal in amount to the difference between (i) the Fair Market Value
(at date of surrender) of the shares for which the surrendered option or portion
thereof is at the time exercisable  and (ii) the aggregate option price  payable
for  such shares.  The distribution to  which an option  holder becomes entitled
under this Section may be made in

                                      A-8
<PAGE>
shares of Common Stock or Restricted  Common Stock, valued at Fair Market  Value
at  the date of surrender, in  cash, or partly in shares  and partly in cash, as
the Committee, in its sole  discretion, deems appropriate. The option  surrender
provisions  of this Section  will not apply  to options granted  pursuant to the
Automatic Option Grant provisions of this Plan.

    (b)  LIMITED STOCK APPRECIATION RIGHTS.  If outstanding options of Cetus for
which Substitute  Options are  issued pursuant  to Section  III(c) have  Limited
Stock  Appreciation Rights ("LSARs") attached thereto, then each such LSAR shall
be  honored  by  the  Corporation  in  accordance  with  its  terms  and  remain
exercisable  for a  period of  60 days following  the date  that stockholders of
Cetus approve the  Merger; provided, however,  that if the  LSAR was  originally
granted  within 6 months of the date that Cetus stockholders approve the Merger,
then the LSAR will be exercisable for  a period of 60 days following  expiration
of  such 6-month period. Upon  expiration of the applicable  60 day period, each
such LSAR not previously exercised shall  expire. Upon exercise of an LSAR,  the
related  option will  be cancelled, and  Chiron will  pay to the  LSAR holder an
amount in  cash for  each share  with respect  to which  the LSAR  is  exercised
determined in accordance with the terms of the Cetus Prior Plans.

XIV.  REPURCHASE RIGHTS

    The  Committee may, in  its discretion, establish  as a term  of one or more
awards granted under the  Plan that the Corporation  (or its assigns) will  have
the  right, exercisable upon the award  holder's termination of employment with,
or  cessation  of  services  for,  the  Corporation  and  its  subsidiaries,  to
repurchase  at the original price  paid, if any, for  such shares of (1) Company
Stock acquired by the award holder pursuant to the granted award, or (2)  Common
Stock into which acquired Restricted Common Stock may have been converted or for
which Restricted Common Stock may have been exchanged. Any such repurchase right
will  be exercisable  by the  Corporation (or its  assigns) upon  such terms and
conditions (including provisions for the expiration of such right in one or more
installments) as the  Committee may  specify in the  instrument evidencing  such
right.  The Committee will also have full power and authority to provide for the
automatic termination of  the Corporation's  repurchase rights, in  whole or  in
part,  thereby accelerating the  vesting of any  or all of  the purchased shares
(other than purchased  shares obtained  pursuant to the  Automatic Option  Grant
provisions  of this Plan) upon the occurrence of any change in control specified
in Article XI.

XV.  RIGHT OF FIRST REFUSAL

    The Committee may, in  its discretion, establish  as a term  of one or  more
awards  granted under the Plan that the Corporation has a right of first refusal
with respect to the proposed disposition  by the award holder (or any  successor
in interest by reason of purchase, gift or other mode of transfer) of any shares
of (1) Company Stock acquired by the award holder pursuant to the granted award,
or  (2) Common Stock into which purchased  Restricted Common Stock may have been
converted or for which acquired Restricted Common Stock may have been exchanged.
Any such right of first  refusal will be exercisable  by the Corporation or  its
assigns  in accordance with the terms and conditions specified in the instrument
evidencing such right.

XVI.  EFFECTIVE DATE AND TERM OF PLAN

    (a)  EFFECTIVE DATE.  The Plan is effective on the date that it is  approved
by the Corporation's stockholders.

    (b)   TERM.  Incentive Options may be granted under the Plan only within ten
years of  the  Effective Date  of  the Plan.  Subject  to this  limitation,  the
Committee  may grant awards under the Plan  at any time after the Effective Date
of the Plan and before the Plan is terminated by the Board.

XVII.  AMENDMENT OR DISCONTINUANCE

    (a)  BOARD.  The Board may  amend, suspend or discontinue the Plan in  whole
or  in  part at  any  time; provided,  however, that  (a)  except to  the extent
necessary to qualify as Incentive Options  any or all options granted under  the
Plan  that are intended to so qualify,  such action may not, without the consent
of the award  holder, adversely affect  rights and obligations  with respect  to
awards outstanding under the Plan; (b) the provisions of the Plan concerning the
eligibility  of non-employee  members of  the Board  for awards  and the amount,
price and timing of Automatic Option Grants  under this Plan may not be  amended
more than once

                                      A-9
<PAGE>
every  six months, other  than to comport  with changes in  the Internal Revenue
Code or rules thereunder; and (c) the Board may not, without the approval of the
Corporation's stockholders  (1)  materially increase  the  number of  shares  of
Company  Stock subject to awards under the  Plan (unless necessary to effect the
adjustments required under Section IV(c)), (2) materially modify the eligibility
requirements for  awards under  the Plan,  or  (3) make  any other  change  with
respect  to which the Board determines  that stockholder approval is required by
applicable law or regulatory standards.

    (b)  COMMITTEE.  The Committee will have full power and authority to  modify
or  waive any or all of the  terms, conditions or restrictions applicable to any
outstanding award  (other  than Automatic  Option  Grants), to  the  extent  not
inconsistent with the Plan.

    (c)  SUBSTITUTE OPTIONS.  Substitute Options will be subject to amendment in
accordance with the terms of this Plan.

XVIII.  NO OBLIGATION

    Nothing  contained in the Plan  (or in any award  granted under this Plan, a
Chiron Prior  Plan  or a  Cetus  Prior Plan)  shall  confer upon  any  employee,
consultant, or independent contractor any right to continue in the employ of, or
to  provide  services  to, the  Corporation  or  any affiliate  or  constitute a
contract or  agreement  of employment  or  for  the provision  of  services,  or
interfere in any way with the right of the Corporation or an affiliate to reduce
such  employee's, consultant's or independent contractor's compensation from the
rate in existence at the time of the  granting of an award or to terminate  such
employee's,  consultant's or independent contractor's  employment or services at
any time, with or  without cause; but  nothing contained in the  Plan or in  any
award granted under this Plan shall affect any contractual rights of an employee
pursuant to a written employment agreement.

XIX.  USE OF PROCEEDS

    The  cash proceeds  received by the  Corporation pursuant  to awards granted
under the Plan will be used for general corporate purposes.

XX.  COMPLIANCE

    (a)   FEDERAL  AND  STATE  LAWS.   No  option  may  be  exercised,  and  the
Corporation  will not be obligated to issue stock under any award unless, in the
opinion of  counsel  for the  Corporation,  such  exercise and  issuance  is  in
compliance with all applicable federal and state securities laws. As a condition
to  the grant of  any award, or  to the issuance  of stock under  any award, the
Committee may require that the award holder agree to comply with such provisions
of federal and state securities laws as  may be applicable to such grant, or  to
the  sale of  stock acquired  pursuant to  the Plan,  and that  the award holder
deliver  to  the  Corporation  a  written  agreement,  in  form  and   substance
satisfactory to the Corporation and its counsel, implementing such agreement.

    (b)    INFORMATION.   The  Corporation  will  furnish to  each  award holder
participating in the Plan (other  than a key employee or  a director) a copy  of
the Corporation's Annual Report to Stockholders for the most recent fiscal year,
and  additional copies will be furnished,  without charge, to such award holders
upon request to the Secretary of the Corporation.

                                      A-10
<PAGE>
                                   APPENDIX A
           SPECIAL PROVISIONS RELATED TO 1995 CIBA-GEIGY TRANSACTION

    Those persons holding options  to acquire shares of  Common Stock under  the
Corporation's  1991  Stock Option  Plan  on November  20,  1994 are  granted the
following rights ("Rights") with respect to each such option:

    (i) the right to receive upon  the closing of the tender offer  contemplated
under  the Investment Agreement entered into  on such date among the Corporation
and Ciba-Geigy  Limited, Ciba-Geigy  Corporation and  Ciba Biotech  Partnership,
Inc.  (the "Closing") a cash payment equal to (A) 37.33% of the number of shares
of Common  Stock with  respect to  which  each such  option would  first  become
exercisable  in calendar year 1995 multiplied by (B) the difference between $117
per share and the exercise price per  share of such option with respect to  such
shares and

    (ii)  with respect to the  remaining shares of Common  Stock subject to each
such option, the right, exercisable at any  time after the later of the  Closing
or  the date that such an option  first becomes exercisable with respect to such
shares, to surrender  that portion  of such option  relating to  37.33% of  such
shares in return for a cash payment equal (A) to the difference between $117 per
share  and the  exercise price per  share of  such option multiplied  by (B) the
number of shares with respect to  which such option is so surrendered.  However,
the grant and exercise of any such right with respect to any officer or director
subject to Section 16 of the Securities Exchange Act of 1934 shall be subject to
stockholder  approval  of the  grant of  such rights  at the  Corporation's 1995
stockholder meeting. The grant  of such rights, which  are made with respect  to
1,858,776  optioned shares shall be in addition to, and shall not count against,
the aggregate and annual limits  on the number of  shares with respect to  which
other  awards under  the Plan  may be  made to  all individuals  and/or a single
individual.

                                      A-11
<PAGE>
                                                                         ANNEX 2
                               CHIRON CORPORATION
             1995 EXECUTIVE OFFICER VARIABLE CASH COMPENSATION PLAN

    This  1995 Executive Officer Variable Cash Compensation Plan (the "Plan") is
established by Chiron  Corporation (the  "Company") effective  for fiscal  years
beginning after December 31, 1994.

1.  PURPOSE

    The purposes of the Plan are to:

    (A) Promote the interests of the Company.

    (B)  Provide incentives  and rewards  to senior  executives, as  a group and
       individually, who are largely responsible for the management, growth  and
       profitability of the Company.

    (C)  Focus incentives upon building value for stockholders by linking senior
       executive compensation to  the Company's performance  as measured by  net
       income and the market value of the Company's stock.

2.  ADMINISTRATION

    The  Plan will be administered by  the Company's Compensation Committee (the
"Committee") or  a  subcommittee  thereof that  satisfies  the  requirements  of
Section  162(m)  of the  Internal Revenue  Code of  1986 or  successor provision
("Section 162(m)"). The  Committee will  have full authority  to administer  the
Plan,  including authority to  interpret and construe  any relevant provision of
the Plan,  determine  eligibility for  an  award and  to  adopt such  rules  and
regulations  as it may deem necessary. Decisions  of the Committee are final and
binding on all  persons who have  an interest  in the Plan.  Should any  further
limitation  on  bonuses  payable under  the  Plan  be necessary  to  satisfy the
requirements of Section 162(m) under final regulations thereunder in order  that
compensation  paid under the  Plan be performance-based,  such limitations shall
apply.

3.  ELIGIBILITY AND PARTICIPATION

    (A) The executives eligible to participate  in the Plan for any fiscal  year
       shall  be each officer of  the Company at the  level of Vice President or
       above.

    (B) Participants are approved for each fiscal year by the Committee by  name
       or  position and will  not be eligible  for an award  for any fiscal year
       unless explicitly approved for such fiscal year. Participants may, at the
       discretion of the Committee, be approved for participation for part of  a
       fiscal year on a pro-rata basis.

    (C) No executive shall participate in the Plan for any fiscal year if he/she
       participates  in any other  Company- sponsored incentive,  sales or bonus
       plan for that fiscal year, unless  such participation is approved by  the
       Committee.

    (D)  If an  executive's employment is  terminated during a  fiscal year, the
       Committee may, in its sole discretion, reduce or cancel the participation
       of such  executive  for  that  year.  Absent  special  circumstances,  no
       participant  may receive any award under the  Plan for any fiscal year if
       he/she terminates employment before the end  of that fiscal year for  any
       reason  other than  Company-approved retirement  after attaining  age 65,
       death, disability or involuntary termination without cause.

4.  DETERMINATION OF BONUSES

    (A)  The  Committee  shall  establish  a  target  bonus  for  each  eligible
       participant, either by name or position, for such fiscal year, payable if
       a  specified Company performance goal is  satisfied for such fiscal year.
       The target bonus payable to any Participant for any fiscal year shall  be
       a  specified percentage (not to exceed 150%) of that participant's salary
       for the fiscal year,  but in no event  shall exceed $1,000,000. Both  the
       specified  percentage  and  the  Company performance  goal  for  a fiscal

                                      A-12
<PAGE>
       year shall be determined  by the Committee within  the first ninety  (90)
       days of such fiscal year of the Company (or within such earlier period as
       shall be required under Section 162(m)).

    (B)  The performance goal for each fiscal year  shall be based on one of the
       following measures of the Company's performance: (i) the achievement of a
       specified closing or average closing price of Company common stock,  (ii)
       the  absolute or  percentage increase in  the closing  or average closing
       price of  Company  common stock  and/or  one  or more  of  the  following
       measures  of the Company's net income  for such fiscal year determined in
       accordance with generally accepted accounting principles as  consistently
       applied  by the Company: absolute net  income or a percentage or absolute
       dollar increase in  net income,  earnings per  share or  a percentage  or
       absolute  dollar increase in earnings per share, or return on equity or a
       percentage or absolute dollar increase in return on equity. The Committee
       may provide  for  alternative  levels  of  bonus  depending  on  relative
       performance toward a performance goal. The Committee may establish a goal
       based  on one or  more measures of  net income or  may establish multiple
       goals based on more than one measure, but any bonus payable must be based
       on the satisfaction of at least one goal.

    (C) For purposes of this Plan, net income shall be net income of the Company
       and  its  consolidated  subsidiaries  as  reported  by  the  Company  and
       certified  by its  independent public  accountants, but  the Committee in
       fixing any goal may exclude  any or all of the  following if they have  a
       material  effect on  annual net income:  events or  transactions that are
       either  unusual  in   nature  or  infrequent   in  occurrence  (such   as
       restructuring\reorganization  charges,  the sale  or discontinuance  of a
       business  segment,  the  sale  of  investment  securities,  losses   from
       litigation,  the cumulative  effect of changes  in accounting principles,
       and natural disasters), depreciation, interest or taxes.

    (D) Final payouts  are subject to  the approval of  the Committee and  shall
       occur  as soon  as practical after  the close of  the Company's financial
       books for the fiscal year. The Committee reserves the right to reduce  or
       cancel any payout that would otherwise be due to a participant if, in its
       sole discretion, the Committee deems such action warranted based on other
       circumstances   relating  to  the  performance  of  the  Company  or  the
       participant.

5.  DEFERRAL OF BONUSES

    (A) The Committee may, subject to such limits as the Committee may  specify,
       permit  a  participant in  the Plan  to defer  all or  part of  the bonus
       awarded to  him/her with  respect to  any fiscal  year by  executing  and
       delivering  to  the  Company a  deferral  election form  provided  by the
       Committee no later  than the date  specified in the  notification to  the
       participant of his/her participation for such fiscal year.

    (B) The deferred bonus will be credited to a special book account maintained
       for  each participant and will accrue earnings based on a reasonable rate
       of interest or on one  or more predetermined actual investments  (whether
       or  not assets  associated with the  amount originally  owed are actually
       invested therein) such  that the amount  payable by the  employer at  the
       later  date will  be based  on the  actual rate  of return  of a specific
       investment (including any decrease as well  as any increase in the  value
       of  an  investment).  Distribution  of the  deferred  bonus  plus accrued
       interest will be made  at such time  or times and in  such manner as  the
       participant  shall specify at the time he/she files the deferral election
       forms, subject,  however, to  such restrictions  and limitations  as  the
       Committee may from time to time impose.

    (C)  The obligation to pay a deferred bonus plus earnings shall at all times
       be an unfunded and unsecured  obligation of the Company. The  participant
       and his/her beneficiary(ies) shall look exclusively to the general assets
       of the Company, as general creditors of the Company. The Plan is intended
       to  be unfunded for  purposes of the  Employee Retirement Income Security
       Act of 1974 and the Internal Revenue Code of 1986. The participant  shall
       have  no  right to  assign, pledge  or encumber  his/her interest  in the
       amount credited  to  the deferred  bonus  account. The  participant  may,
       however,  designate  one or  more  beneficiaries to  receive  the account
       balance in the event of his/her death.

                                      A-13
<PAGE>
6.  AMENDMENT/TERMINATION

    The Company  hereby reserves  the right,  exercisable by  the Committee,  to
amend  the Plan at any  time and in any respect  or to discontinue and terminate
the Plan in whole  or in part at  any time, subject to  Section 7. Amendment  or
termination  may be effective with respect to  any amount which has not yet been
paid out,  except that  amounts which  have been  credited to  a deferred  bonus
account  shall be paid  out in accordance with  the applicable deferral election
or, if the Committee so determines upon termination of the Plan, distributed  to
such  participant as soon  as practicable after  termination of the  Plan. In no
event shall any award be increased,  other than pursuant to Section 4(C),  after
the   last  day   that  an  award   must  be  specified   for  qualification  as
performance-based compensation under Section 162(m).

    No provision of the Plan shall be  deemed to constitute a commitment of  the
Company  to pay, or to confer any contractual or other rights upon a participant
to receive a bonus award for any one or more fiscal years or to confer upon  any
participant  any right to continue in the employ of the Company or to constitute
any contract or  agreement of employment  or to  interfere in any  way with  the
right  of the Company to terminate a  participant's employment at any time, with
or without  cause, but  nothing contained  herein shall  affect any  contractual
right of a participant pursuant to a written employment agreement.

7.  TERM AND SHAREHOLDER APPROVAL

    In no event shall any award be made under the Plan for any fiscal year after
the  fiscal year  beginning in  calendar year 1999.  The Plan,  awards under the
Plan, and any amendment to the Plan  which would change the class of  executives
who  are eligible to receive awards under  the Plan or the permissible amount of
such awards shall be subject to  approval of the Company's shareholders in  such
manner and with such frequency as shall be required under Section 162(m).

                                      A-14
<PAGE>
                               CHIRON CORPORATION
          THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

    The  undersigned hereby  appoints Dr.  William J.  Rutter and  Dr. Edward E.
Penhoet, and each of them, with full  power of substitution, the proxies of  the
undersigned  to  vote all  shares  of Common  Stock  of Chiron  Corporation (the
"Company") which the undersigned  is entitled to vote  at the Annual Meeting  of
Stockholders  of  the  Company  to  be held  at  1450  53rd  Street, Emeryville,
California, on  May  18,  1995  at  10:00  a.m.,  and  at  any  adjournments  or
postponements  thereof, with the same force  and effect as the undersigned might
or could do if personally present thereat:

                                                                I PLAN TO ATTEND
                                                                 THE MEETING
                                                                     / /

1.  ELECTION OF DIRECTORS     / / FOR all nominees      / / WITHHOLD AUTHORITY
    (THE BOARD OF DIRECTORS   listed below                to vote for all
    RECOMMENDS A VOTE FOR.)     (except as marked to      nominees listed below.
                                the contrary below).

   INSTRUCTION: TO WITHHOLD AUTHORITY TO VOTE FOR ONE OR MORE INDIVIDUAL
                NOMINEES, STRIKE A LINE THROUGH THE NOMINEE'S NAME IN THE LIST
                BELOW.

Dr. Gilbert F. Amelio - Dr. Edward E. Penhoet - Dr. Henri Schramek - Mr. Pierre
                                     Douaze

2.  Proposal to approve amended  Chiron 1991 Stock Option  Plan as set forth  in
    the   Chiron  Corporation  Proxy   Statement  for  the   Annual  Meeting  of
    Stockholders to be held May 18,  1995. (The Board of Directors recommends  a
    vote FOR.)

            / /  FOR            / /  AGAINST            / /  ABSTAIN

3.  Proposal  to adopt  the Chiron  Corporation 1995  Executive Officer Variable
    Cash Compensation  Plan  as  set  forth  in  the  Chiron  Corporation  Proxy
    Statement  for the Annual Meeting  of Stockholders to be  held May 18, 1995.
    (The Board of Directors recommends a vote FOR.)

            / /  FOR            / /  AGAINST            / /  ABSTAIN

                          (CONTINUED ON REVERSE SIDE)
<PAGE>
4.  Proposal to ratify the selection of KPMG Peat Marwick as independent  public
    accountants  for the Company  for the fiscal year  ending December 31, 1995.
    (The Board of Directors recommends a vote FOR.)

            / /  FOR            / /  AGAINST            / /  ABSTAIN

5.  In their discretion,  the Proxies  are authorized  to vote  upon such  other
    business as may properly come before the meeting.

    THIS  PROXY  WHEN PROPERLY  EXECUTED WILL  BE VOTED  IN THE  MANNER DIRECTED
HEREIN BY THE UNDERSIGNED STOCKHOLDER. IF NO DIRECTION IS MADE, THIS PROXY  WILL
BE VOTED FOR PROPOSALS 1, 2, 3 AND 4.
                                                 Dated ___________________, 1995
                                                     (Be Sure to Date Proxy)
                                                 _______________________________
                                                            Signature
                                                 _______________________________
                                                            Signature

                                                 Please  sign  exactly  as  name
                                                 appears at  left.  When  shares
                                                 are held by joint tenants, both
                                                 should  sign.  When  signing as
                                                 attorney, executor,
                                                 administrator,   trustee,    or
                                                 guardian,   please   give  full
                                                 title as such. If a
                                                 corporation,  please  sign   in
                                                 full corporate name by
                                                 President  or  other authorized
                                                 person.   If   a   partnership,
                                                 please sign in full partnership
                                                 name by authorized person.

 PLEASE MARK, SIGN, DATE AND RETURN THE PROXY CARD PROMPTLY, USING THE ENCLOSED
                                    ENVELOPE


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