SecProbe.io

Mail Stop 6010
September 15, 2008
 Uli Hacksell, Ph.D.  Chief Executive Officer  ACADIA Pharmaceuticals Inc.  3911 Sorrento Valley Boulevard San Diego, CA 92121
Re: ACADIA Pharmaceuticals Inc.
  Registration Statement on Form S-3
Filed September 15, 2008
  File No. 333-153347

Dear Dr. Hacksell:

We have limited our review of your filing to the issue we have addressed in our
comment.  Where indicated, we think you shoul d revise your document in response to
this comment.  If you disagree, we will cons ider your explanation as to why our comment
is inapplicable or a revision is unnecessary.  Please be as detailed as necessary in your
explanation.
Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comment or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.
 General

 We note that the registration statement rela tes to 7,422,364 shares of common stock that
may be sold by either the selling stockholder or  the registrant.  The registration statement
may not register shares to be sold by the selling stockholder or, in th e alternative, by the
registrant.  Instead, the regist ration statement must separately identify the shares to be
sold by the selling stockholder and the shares to be sold by the registrant.  Please revise
your registration statement accordingly.
* * *

As appropriate, please amend your regist ration statement in response to this
comment.  You may wish to provide us with ma rked copies of the amendment to expedite
our review.  Please furnish a c over letter with your amendment that keys your response to

Uli Hacksell, Ph.D.
ACADIA Pharmaceuticals Inc.
September 15, 2008 Page 2

our comment and provides any requested info rmation.  Detailed cover letters greatly
facilitate our review.  Please understand th at we may have additional comments after
reviewing your amendment a nd response to our comment.
We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Act of 1933 and that they have  provided all information investors require
for an informed investment decision.  Since the company and its management are in
possession of all facts relating to a company’ s disclosure, they are responsible for the
accuracy and adequacy of the disclosures they have made.
Notwithstanding our comments, in the even t the company requests acceleration of
the effective date of the pending registration statement, it should furnish a letter, at the time of such request, acknowledging that:   ‚ should the Commission or the staff, acting purs uant to delegated authority, declare the
filing effective, it does not foreclose th e Commission from taking any action with
respect to the filing;
 ‚ the action of the Commission or the staff, acting pursuant to delegated authority, in
declaring the filing effective,  does not relieve the company from its full responsibility
for the adequacy and accuracy of the disclosure in the filing; and
 ‚ the company may not assert staff comments a nd the declaration of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.
  In addition, please be advi sed that the Division of En forcement has access to all
information you provide to the staff of the Di vision of Corporation Finance in connection
with our review of your filing or in response to our comments on your filing.
We will consider a written request for acceleration of the effective date of the
registration statement as conf irmation of the fact that t hose requesting acceleration are
aware of their respective re sponsibilities under the S ecurities Act of 1933 and the
Securities Exchange Act of 1934 as they rela te to the proposed public offering of the
securities specified in the above registration statement.  We will act  on the request and,
pursuant to delegated authority, grant acce leration of the effective date.
We direct your attention to Rules 46 0 and 461 regarding requesting acceleration
of a registration statement.  Please allow ad equate time after the filing of any amendment
for further review before submitting a request for acceleration.  Please provide this request at least two business days in a dvance of the requested effective date.

Uli Hacksell, Ph.D.
ACADIA Pharmaceuticals Inc.  September 15, 2008 Page 3

Please contact Sebastian Gomez Abero at (202) 551-3578 or me at (202) 551-
3715 with any questions.          S i n c e r e l y ,             J e f f r e y  P .  R i e d l e r          A s s i s t a n t  D i r e c t o r   cc: Glenn F. Baity
Vice President and General Counsel ACADIA Pharmaceuticals Inc. 3911 Sorrento Valley Boulevard San Diego, CA 92121   D. Bradley Peck J. Patrick Loofbourrow Sean M. Clayton Cooley Godward Kronish LLP
4401 Eastgate Mall
San Diego, CA 92121-9109