Exhibit 99 1998 AMENDMENT TO THE ------------------------ 1997 EMPLOYEE STOCK PURCHASE PLAN ------------------------------------- OF INCYTE PHARMACEUTICALS, INC. ---------------------------------- THIS AMENDMENT amends the 1997 Employee Stock Purchase Plan of Incyte Pharmaceuticals, Inc. (the "Company"), originally adopted by the Board of Directors of the Company on February 27, 1997 (the "Plan"). Unless specifically otherwise defined, each term used herein shall have the meaning assigned to such term in the Plan. WHEREAS, the Board of Directors has determined that it is in the best interests of the Company to amend the Plan to provide for a six-month employment eligibility period, commencing with the Offering Period beginning May 1, 1998: NOW THEREFORE, the Plan is hereby amended as follows: Effective as of May 1, 1998 and concurrent with the Offering Period commencing on such date, Section 3(a) of the Plan shall be amended and restated to read in its entirety as follows: "Any Employee who has been employed by the Company for six months or more on a given Enrollment Date shall be eligible to participate in the Plan." To record the adoption of this Amendment to the Plan by the Board of Directors, as of April 28, 1998, the Company has caused its authorized officer to execute the same. INCYTE PHARMACEUTICALS, INC. By /s/ ROY A. WHITFIELD --------------------------------- Roy A. Whitfield As its Chief Executive Officer -----------------------------