CUSIP 09058v 10 3

BIOCRYST PHARMACEUTICALS, INC. This Corporation will furnish without charge to each stockholder who so requests, a copy of the designations, powêÍs, preferences and relative, participating, optional or other special rights of each class of stock or series thereof of the Corporation and the qualifications, limitations or restrictions of such preferences and/or rights. Any such requests may be addressed to the Corporation or its Transfer Agent. The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in fuIl according to applicable laws or regulations: TEN COM- as tenaûts in common UNIF GIFT MIN ACT ...Custodian.. (Cust) (Minor) T.EN ENT as tenants by the entireties Under Uniform Gifts to Minors JT ^TEN as ^joint tenants with right of survivorship and not as tenants in common Additional abbreviations may also be used though not in the above list. For ^qtalue receic)ed, bereby sell, assþ urd naufer unn PLEASE INSERT SOCIAL SECURIfi OR OTHER IDENTIFYING NUMBER OF ASSIGNEE PLEASE PRINT OR TYPEIøRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE OF ASSIGNEE Sb¿res of the Capital Stock reÞresentedby the within Certificate and do bereby irreuocably constitute and aÞÞoint Attomey to traßfer the said stock on tbe boolc of the witbin-named Corþoranon ^wtth full þower ^{of substiunon in tbe} þremises. Dated: Signature THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS \ß/RITTEN UPON THE FACE OF THE CERTIFICATE. IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CFI-ANGE WIIATEVER. The signature(s) of the assignor(s) must be guamnteed hereon by a panicipant in either the Securities Tmfer Agents Medallion Procram (“STAMP”), the Stæk Exchanges Medallion P¡ogram-(“SEMP”) or the Ñew York StocË Exchange Medallion Signature Program (“MSP”). This certificate also evidences and entitles the holder hereof to certain rights as set forth in a Rights Agreement between BioCryst Pharmaceuticals, Inc. and American Stock Transfer & Trust Company, dated as ^of June ^{14, 2002 (the} “Rights Agreement”), the terms of which are hereby incorporated herein by reference and a copy of which is on file at the principal executive offices of BioCryst Pharmaceuticals, Inc. Under certain circumstances, as set forth in the Rights Agreement, such Rights will be evidenced by separate certificates and will no longer be evidenced by this certificate. BioCryst Pharmaceuticals, Inc. will mail to the holder of this certificate a copy of the Rights Agreement witl¡out charge after receipt of a w¡itten request therefor. Under certain circumstances, as set forth in the Rights Agreement (including, without limitation, Section 7(e) thereofl, Rights issued to or Beneficially Owned by Acquiring Persons or their Affiliates or Associates (as such terrns are defined in the Agreement) or any subsequent holder of such Rights shall be null and void and may not be exercised by or transferred to any Person.