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Preliminary Proxy Statement

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Definitive Proxy Statement

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Definitive Additional Materials

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Meeting Information

Meeting Type:

      Annual Meeting of Stockholders

For holders as of:

      04/09/09

Date:      06/01/09      Time: 9:00 AM PDT

Location:     Cerus Corporation

                     2411 Stanwell Drive

                     Concord, CA 94520

Meeting Directions: For driving directions to the meeting, please visit: www.cerus.com/index.cfm/contact/ Map_&_Directions

CERUS CORPORATION

ATTN: LORI ROLL

2411 STANWELL DRIVE

CONCORD, CA 94520

You are receiving this communication because you hold shares in Cerus Corporation.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper or electronic copy.

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice for instructions on obtaining a paper or electronic copy of the proxy materials and voting instructions.

Notice and Proxy Statement        Annual Report which includes the Annual Report on Form 10-K

Have the Control Number available (located on the following page) and visit www.proxyvote.com.

If you want to receive a paper or electronic copy of the proxy materials, you must request one. There is NO charge for requesting a copy. Please have the Control Number available and choose one of the following methods to make your request:

1) BY INTERNET:

www.proxyvote.com

2) BY TELEPHONE:

1-800-579-1639

3) BY E-MAIL*:

sendmaterial@proxyvote.com

    You may also use the above methods to request documents relating to future stockholder meetings.

*   If requesting materials by e-mail, please send a blank e-mail with the Control Number (located on the following page) in the subject line. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor.

To facilitate timely delivery, please make the request as instructed above on or before 05/18/09.

— How To Vote —

Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the proxy materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote over the Internet, go to www.proxyvote.com to complete your electronic proxy card. Have the Control Number available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper or electronic copy of the proxy materials, which will include a proxy card.

The Board of Directors recommends you vote “FOR” Proposals 1 and 2.

1.

To elect the following nominees for director to the Board of Directors of the Company, to hold office until the 2012 Annual Meeting of Stockholders.

Nominees:

01) B. J. Cassin

02) William R. Rohn

2.

To ratify the selection by the Audit Committee of the Board of Directors of Ernst & Young LLP as the independent registered public accounting firm of the Company for its fiscal year ending December 31, 2009.

Although the Board of Directors knows of no other matters that will be presented for consideration at the Annual Meeting, if any other matters are properly brought before the Annual Meeting, it is the intention of the persons named in the proxy to vote on those matters in accordance with their best judgment.