FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Walther Gene   2. Issuer Name and Ticker or Trading Symbol CHIRON CORP [CHIR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) V.P.; President, Chiron BT (Last) (First) (Middle) 4560 HORTON STREET 3. Date of Earliest Transaction (Month/Day/Year) 02/17/2006 (Street) EMERYVILLE, CA 94608-2916 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Units (1)

(2)

02/17/2006

A(3)

2,200

02/17/2007(4)

02/16/2010

Common Stock

2,200

$ 0

2,200

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Walther Gene 4560 HORTON STREET EMERYVILLE, CA 94608-2916			V.P.; President, Chiron BT

Signatures

Gene W. Walther by Naima Robinson as Atty-in-Fact		02/22/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Each unit pertains to one share of the Issuer's common stock and may be settled either in cash or in stock based on date on which settlement occurs. Settlement will occur as the units vest, and to the extent such settlement occurs prior to the closing of the acquisition of the Issuer by Novartis AG, the payment will be made in shares of the Issuer's common stock; otherwise, the units will be assumed by Novartis and payment will be made in cash based on the consideration paid per share of the Issuer's common stock in the Novartis acquisition.
(2)	One-for-One
(3)	Shares of the Issuer's common stock which become issuable upon the vesting of the units will be withheld by the Issuer in satisfaction of the applicable withholding taxes, unless the Reporting Person elects to pay such taxes in cash.
(4)	The units will vest in four equal, successive annual installments upon the Reporting Person's completion of each year of employment with the Issuer over the four-year period measured from the Grant Date. However, the units will vest in full on an accelerated basis upon an acquisition of the Issuer by a merger or asset sale in which the units are not assumed or upon the termination of the Reporting Person's employment with the Issuer under certain prescribed circumstances following certain changes in control or ownership of the Issuer (including the Novartis acquisition) in which the units are assumed.

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