Exhibit 10.725

NOVARTIS AG        WRITTEN CONSENT AND APPROVAL        Effective as of October 21, 2002

AMENDMENTS TO GOVERNANCE AGREEMENT AND BYLAWS

WHEREAS, Sections 2.04 (b)(iv) and (vii) of that certain Governance Agreement dated as of November 20, 1994 between Chiron Corporation
("Chiron" or the "Company") and Novartis AG, requires the approval of a majority of the Investor Directors to amend the Bylaws of Chiron or to establish any committee of the Board of Directors of
Chiron other than as provided in Section 2.03(b) (i) through (v) of the Governance Agreement;

WHEREAS,
Section 2.03(b)(vi) of the Governance Agreement provides that the Board of Directors of Chiron may establish such other committees of the Board as the Board deems
necessary or desirable, provided that such committees are established in compliance with the terms of the Governance Agreement;

WHEREAS,
Section 3.11 of Chiron's Bylaws currently provides for the establishment of five committees of the Board, and the Board has deemed it appropriate and in the best
interests of Chiron to amend Section 3.11 of the Bylaws and Section 2.03 (b) of the Governance Agreement to establish an additional committee of the Board called the "Executive
Committee", which committee shall be established and constituted with such powers and authority in accordance with Sections 2.03(a) and (c) of the Governance Agreement;

NOW,
THEREFORE, BE IT RESOLVED, that the amendments to Section 2.03(b) of the Governance Agreement and Section 3.11 of Chiron's Bylaws in substantially the form attached
hereto asAnnex 1andAnnex 2, are hereby approved;

IN
CONSIDERATION OF THE FOREGOING, Novartis AG hereby approves the establishment of the Executive Committee of Chiron's Board of Directors, and corresponding amendments to the Governance
Agreement with Chiron and Chiron's Bylaws, effective as of October 21, 2002.

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ANNEX 1

CHIRON CORPORATION  Governance Agreement Dated November 20, 1994 with Novartis AG

Section 2.03(b) of the Governance Agreement dated November 20, 1994 with Novartis AG (the "Governance Agreement") is hereby amended, effective as of
October 21, 2002, toadda new subsection, 2.03(vi) to read in its entirety, as follows:



Subsection
2.03(vi) is herebyre-designatedas subsection 2.03(vii) to read in its entirety, as follows:



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ANNEX 2

CHIRON CORPORATION  Bylaws, as amended

Section 3.11 of the Bylaws of Chiron Corporation is hereby amended, effective as of October 21, 2002, to read in its entirety, as follows:

3.11Committees.Section 2.03 of the Governance Agreement provides that the following committees of the
Board of Directors shall be formed and administered: (i) an Audit Committee; (ii) a Nominating
Committee; (iii) a Strategic Planning Committee; (iv) a Compensation Committee; (v) a Stock Option Plan Administration Committee; and (vi) an Executive Committee. Such
committees of the Board of Directors shall be formed, maintained and administered in accordance with the terms of said Section 2.03 of the Governance Agreement, which provisions are
incorporated herein and made a part of these Bylaws. All committees of the Board of Directors not specifically provided for in said Section 2.03 shall be constituted in accordance with
Section 2.03(c) of the Governance Agreement.

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