**Exhibit 10.615**

 
| **CHIRON** | **Howard H.****Pien**                  |
|------------|----------------------------------------|
|       | President  and Chief Executive Officer |

 

 

February 28, 2005

 

Jack Goldstein

[Residence address]

 

 

Dear Jack:

 

This letter amends incertain respects your offer letter dated August 16, 2002 and confirms certain changes in your compensation as a result of your appointment as Presidentand Chief Operating Officer of Chiron.

 

Effective February 28, 2005,your salary will be $600,000 per annum, paid bi-weekly. TheCompensation Committee approved your AIP bonus for 2004 in the amount of $460,000. That amount will be paid toyou March 14, 2005.

 

You have been awarded aspecial, one-time restricted share right award on 50,000 shares of Chironcommon stock that will vest three years from the date of grant, February 22, 2005,subject to earlier vesting only in the event your employment is involuntarily terminatedby the Company (except for cause). You will receive a letter outlining the otherprovisions of this share right grant from the Law Dept. You will be eligible toreceive annual performance sharegrants under Chiron’s Long Term IncentivePlan (“LTIP”).

 

You have also been awarded astock option grant to purchase 200,000 shares of Chiron common stock. This 2005grant consists of two components: an increasedtarget grant of options on 150,000 shares of Chiron common stock which will beyour target grant going forward and a special promotional grant of options on50,000 shares of Chiron common stock. (You will be eligible for annual grant consideration at this new target level.)The options vest fully over a three-year period, with the first one-third ofthe shares vesting at the one-year anniversary of the date of grant, the secondone-third vesting at the two-year anniversary and the remaining shares vestingon a pro-rated monthly basis over the remaining one year of the vesting period.The exercise price of the option was set at the fair market value (as defined in the Stock Compensation Plan) of a share of Chiron stock on February 22,2005.

 

**CHIRON CORPORATION****•********4560Horton Street****•****Emeryville,****CA****•********94608-2916**

**Tel:510-923-3800****•****Fax:510-923-3151****•****Email: howard_pien@chiron.com**

 

----

 

In the future, yourperformance share and option target levels will only be adjusted in such amanner as would apply to all other executive officers, as approved by the CompensationCommittee in its annual review of executive officer compensation.

 

We have agreed that shouldyour employment be involuntarily terminated because of a job elimination, youwill be eligible until February 19, 2007 for severance in the amount of oneyear’s base salary and target bonus in lieu of any other severance benefit forwhich you might be eligible in such circumstances. Thereafter, for the next six(6) months, the benefit for which you would be eligible as described in theprevious sentence, shall be reduced by one-twelfth each month until August 19,2007.  Thereafter, you will only be eligiblefor benefits as determined under the provisions of Chiron’s Executive SeverancePlan, in the event your employment is involuntarily terminated because of aworkforce reduction or a job elimination. You will continue to be covered byChiron’s Executive Officer Change in Control Severance Plan.

 

You will also continue to beeligible to participate in Chiron’s Annual Incentive Plan (AIP). The Plan, asstructured, has an incentive range for your position from 0% to 200%, with atarget of 100% of base pay, based on overall corporate performance, as assessedby the Compensation Committee.

 

All other provisions of youroffer letter dated August 16, 2002, not otherwise amended by the provisions ofthis letter, remain in place, including specifically the provision for at will employment.

 

The Board and I are pleasedthat you have accepted your new role and look forward to your continuing contributionsto Chiron’s success.

 
| Sincerely,                            |
|---------------------------------------|
|                                  |
| /s/ Howard  H. Pien                   |   |
| Howard H.  Pien                       |
| Chairman and Chief  Executive Officer |

 

Please indicate yourunderstanding of the terms of this offer and your acceptance by signing thisletter and returning it to me as soon as possible.

 
| /s/ Jack  Goldstein |   | 4 March 2005 |
|---------------------|--------|--------------|
| Name                | Date   |

 

----