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                                                                    EXHIBIT 23.1


               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

We consent to the incorporation by reference in this Registration Statement on
Form S-8 pertaining to the Amended and Restated 1998 Equity Compensation Plan of
Arena Pharmaceuticals, Inc. of our report dated May 29, 2000, except for the
last paragraph of Note 10, as to which the date is July 25, 2000, with respect
to the financial statements of Arena Pharmaceuticals, Inc. included in the
Registration Statement (Form S-1 No. 333-35944) of Arena Pharmaceuticals, Inc.
as filed with the Securities and Exchange Commission.

                                            /s/ ERNST & YOUNG, LLP


San Diego, California
September 7, 2000



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