EXHIBIT 31.1

                CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT
                TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Gary A. Lyons, President and Chief Executive Officer of Neurocrine
Biosciences, Inc., certify that:

1. I have reviewed this quarterly report on Form 10-Q of Neurocrine Biosciences,
   Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a
   material fact or omit to state a material fact necessary to make the
   statements made, in light of the circumstances under which such statements
   were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial
   information included in this report, fairly present in all material respects
   the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over
   financial reporting (as designed in Exchange Act Rules 13a-15(f) and
   15d-15(f)) for the registrant and have:

   a) Designed such disclosure controls and procedures, or caused such
      disclosure controls and procedures to be designed under our supervision,
      to ensure that material information relating to the registrant, including
      its consolidated subsidiaries, is made known to us by others within those
      entities, particularly during this period in which this report is being
      prepared; and

   b) Designed such internal control over financial reporting, or caused such
      internal control over financial reporting to be designed under our
      supervision, to provide reasonable assurance regarding the reliability of
      financial reporting and the preparation of financial statements for
      external purposes in accordance with generally accepted accounting
      principles; and

   c) Evaluated the effectiveness of the registrant's disclosure controls and
      procedures and presented in this report our conclusions about the
      effectiveness of the disclosure controls and procedures, as of the end of
      the period covered by this report based on such evaluation; and

   d) Disclosed in this report any change in the registrant's internal control
      over financial reporting that occurred during the registrant's most recent
      fiscal quarter (the registrant's fourth fiscal quarter in the case of an
      annual report) that has materially affected, or is reasonably likely to
      materially affect, the registrant's internal control over financial
      reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our
   most recent evaluation of the internal control over financial reporting, to
   the registrant's auditors and the audit committee of registrant's board of
   directors (or persons performing the equivalent function):

   a) All significant deficiencies and material weaknesses in the design or
      operation of internal control over financial reporting which are
      reasonably likely to adversely affect the registrant's ability to record,
      process, summarize and report financial information; and

   b) Any fraud, whether or not material, that involves management or other
      employees who have a significant role in the registrant's internal
      controls over financial reporting.

Dated: August 4, 2005                /s/ Gary A. Lyons
                                     -------------------------------------
                                     Gary A. Lyons
                                     President and Chief Executive Officer

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