SIAL (MM)

Sigma-Aldrich Corporation will hold its quarterly conference call to discuss second quarter results on Tuesday, July 26, 2011 at 10:00 AM Central Time (11:00 AM Eastern Time).

 Date:    July 26, 2011
 Time:    10:00 AM CT (11:00 AM ET)
 Toll Free:   877-266-0483
 International: 707-287-9342
 Passcode:    37560590

Interested parties may listen via live audio broadcast and view the slide presentation over the Internet available at: http://investor.sigmaaldrich.com/. Users can click the "Webcast" icon to access the file.

Replay will be available July 26, 2011 through August 2, 2011. Replay information is as follows:

Toll Free: 800-642-1687 International: 706-645-9291 Passcode: 37560590

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 8000 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
         314-286-8015
         carrie.fields@sial.com