SIAL (MM)

Sigma-Aldrich Corporation (Nasdaq:SIAL) will hold its Annual Meeting of Shareholders on Tuesday, May 3, 2011, at 11:00 a.m. Central Time (12:00 p.m. Eastern Time).

Date:	May 3, 2011
Time:	11:00 AM CT

Webcast and slide presentation can be accessed at Sigma-Aldrich Corporation's website at http://investor.sigmaaldrich.com.

Sigma-Aldrich is a leading Life Science and High Technology company committed to Enabling Science to Improve the Quality of Life. Its chemical and biochemical products and kits are used in scientific research, including genomic and proteomic research, biotechnology, pharmaceutical development and as key components in pharmaceutical, diagnostic and other high technology manufacturing. The Company has customers in life science companies, university and government institutions, hospitals, and in industry. Over one million scientists and technologists use its products. Sigma-Aldrich operates in 40 countries and has 7900 employees providing excellent service worldwide. For more information about Sigma-Aldrich, please visit its award-winning Web site at http://www.sigma-aldrich.com.

CONTACT: Carrie Fields
         Investor Relations
         +1 314 2868015
         carrie.fields@sial.com