ACADIA PHARMACEUTICALS INC. 3911 SORRENTO VALLEY BOULEVARD SAN DIEGO, CA 92121 August 31, 2001 VIA EDGAR TRANSMISSION United States Securities and Exchange Commission Judiciary Plaza Mail Stop 4-6, Room 4311 450 Fifth Street, N.W. Washington, D.C. 20549-0306 Attn: Jeffrey P. Riedler RE: ACADIA PHARMACEUTICALS INC. REGISTRATION STATEMENT ON FORM S-1 (FILE NO. 333-52492) REQUEST FOR WITHDRAWAL Dear Mr. Riedler: Pursuant to Rule 477 of the Securities Act of 1933, as amended, ACADIA Pharmaceuticals Inc. (the "Registrant") hereby requests withdrawal of its Registration Statement on Form S-1 (SEC File No. 333-52492) filed with the Securities and Exchange Commission on December 21, 2000, and amended on February 5, 2001, on the grounds that current market conditions do not support a public offering of the Registrant's Common Stock at this time. If you should have any questions regarding this application, please contact D. Bradley Peck or Glenn F. Baity of Cooley Godward LLP at (858) 550-6000. Sincerely, ACADIA PHARMACEUTICALS INC. By: /s/ Uli Hacksell ---------------------------------------------- Uli Hacksell, Ph.D. Chief Executive Officer cc: D. Bradley Peck Glenn F. Baity Faye H. Russell Jeffrey C. Thacker N. Sean Harrison