Neurocrine Biosciences (NBIX) 8-K Neurocrine Biosciences Announces the Appointment of

Exhibit 3.1

CERTIFICATE OF AMENDMENT

OF BY-LAWS OF

NEUROCRINE BIOSCIENCES, INC.

(A DELAWARE CORPORATION)

On February 3, 2010, the Board of Directors of Neurocrine Biosciences, Inc. approved the amendment of Section 3.2 of the By-Laws of the corporation to read as follows:

3.2Number of Directors. The Board of Directors shall consist of nine (9) members. The number of Directors may be changed by an amendment to this by-law adopted by the Board of Directors or by the stockholders or by a duly adopted amendment to the certificate of incorporation. The Directors shall be divided into three classes, with the term of office of the first class (Class I Directors), which will initially consist of three (3) Directors, to expire at the 2012 Annual Meeting of Shareholders; the term of office of the second class (Class II Directors), which will initially consist of three (3) Directors, to expire at the 2010 Annual Meeting of Shareholders; the term of office of the third class (Class III Directors), which will initially consist of three (3) Directors, to expire at the 2011 Annual Meeting of Shareholders; and thereafter for each such term to expire at each third succeeding Annual Meeting of Shareholders held after such election.