As independent public accountants, we hereby consent to the incorporation by reference in this registration statement of our report dated February 14, 2000, incorporated by reference in Sigma-Aldrich Corporation's Form 10-K for the year ended December 31, 1999 and to all references to our Firm included in this registration statement.
 

                                                                                                                                                      /s/ Arthur Anderson LLP
                                                                                                                                                      Arthur Andersen LLP
St. Louis, Missouri,
November 13, 2000