- Additional Proxy Soliciting Materials (definitive) (DEFA14A)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

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Exchange Act of 1934 (Amendment No. )

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x		Definitive Additional Materials

¨		Soliciting Material Pursuant to §240.14a-12

SIGMA-ALDRICH CORPORATION

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

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*** Exercise Your Right to Vote ***

Important Notice Regarding the Availability of Proxy Materials for the

Shareholder Meeting to Be Held on May 1, 2012.


SIGMA-ALDRICH CORPORATION				Meeting Information
				Meeting Type: Annual Meeting For holders as of: March 2, 2012 Date: May 1, 2012 Time: 11:00 AM CDT Location: Sigma-Aldrich Corporation Life Science and High Technology Center 2909 Laclede Avenue St. Louis, Missouri 63103


		3050 SPRUCE STREET ST. LOUIS, MO 63103-2564		You are receiving this communication because you hold shares in the above named company. 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 copy (see reverse side). 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 to obtain proxy materials and voting instructions.


				Before You Vote

How to Access the Proxy Materials


						Proxy Materials Available to VIEW or RECEIVE:
						NOTICE AND PROXY STATEMENT ANNUAL REPORT How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please 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 * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (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. Please make the request as instructed above on or before April 17, 2012 to facilitate timely delivery.


								— How To Vote — Please Choose One of the Following Voting Methods

								Vote In Person: Many shareholder 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 meeting 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 now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.


		Voting Items


		This proxy will be voted FOR items 1, 2 and 3 unless otherwise directed, and in the discretion of the proxies, on whatever other business may properly come before the meeting. The Board of Directors recommends a vote FOR each of the director nominees and FOR Proposals 2 and 3.
		1. Election of Directors:
		Nominees:
		1a. Rebecca M. Bergman
		1b. George M. Church
		1c. W. Lee McCollum
		1d. Avi M. Nash
		1e. Steven M. Paul
		1f. J. Pedro Reinhard
		1g. Rakesh Sachdev
		1h. D. Dean Spatz
		1i. Barrett A. Toan
		2. Ratification of the appointment of KPMG LLP as the Company’s independent registered public accountant for 2012
		3. Advisory vote to approve named executive officer compensation