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                                                                   EXHIBIT 10.12

                   AMENDMENT TO COMMON STOCK WARRANT AGREEMENT

   This Amendment to Common Stock Warrant Agreement ("Amendment"), effective as
of March 18, 2002, by and between GenVec, Inc., having offices at 65 West
Watkins Mill Road, Gaithersburg, Maryland 20878 ("Company"), and Cornell
Research Foundation, Inc., having offices at Cornell Business & Technology Park,
20 Thornwood Drive, Suite 105, Ithaca, New York ("Holder"), amends that certain
GenVec, Inc. Common Stock Warrant Agreement by and between Company and Holder
dated May 15, 1998 (the "Warrant Agreement").

   WHEREAS, in accordance with the provisions of the Warrant Agreement, Holder
was granted the right to purchase up to Four Hundred Thousand (400,000) shares
of Company common stock at an exercise price of three dollars ($3.00) per share.

   WHEREAS, as a result of Company stock splits and a recapitalization
subsequent to May 15, 1998, Holder is, as of the effective date of this
Amendment, entitled under Section 7(a) of the Warrant Agreement to purchase up
to One Hundred One Thousand, Six Hundred Ninety-Four (101,694) shares of Company
common stock at an exercise price of eleven dollars and eighty cents ($11.80)
per share, subject to further adjustments under the Warrant Agreement.

   WHEREAS, in consideration of amendments agreed to by the parties to their
Amended and Restated Exclusive License Agreement, the parties desire to amend
the Warrant Agreement as set forth herein below.

   NOW, THEREFORE, Company and Holder agree as follows:

AMENDMENT. This Amendment hereby amends the Warrant Agreement to incorporate the
terms and conditions set forth in this Amendment. The relationship of the
parties shall continue to be governed by the terms and conditions of the Warrant
Agreement, as amended herein; and in the event that there is any conflict
between the terms and conditions of the Warrant Agreement and this Amendment,
the terms and conditions of this Amendment shall control. As used in this
Amendment, all capitalized terms shall have the meanings defined for such terms
in this Amendment or, if not defined in the Amendment, the meanings defined in
the Warrant Agreement.

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MODIFICATIONS TO THE AGREEMENT:

1. In Section 1, lines 4-6 of the Warrant Agreement the phrase "up to 400,000
   shares (the "Warrant Shares"), of the Company's common stock, par value $.01
   per share ("Common Stock"), at an exercise price of three dollars ($3.00) per
   share" is hereby deleted and the phrase "up to 101,694 shares (the "Warrant
   Shares"), of the Company's common stock existing as of the effective Date of
   this Amendment, par value $.001 per share ("Common Stock"), at an exercise
   price of three dollars and sixty cents ($3.60) per share" substituted
   therefor.

2. In Section 2(a) of the Warrant Agreement, the numbers of Warrant Shares set
   forth in clauses (i) through (iii) shall be adjusted proportionately to give
   effect to the stock splits and recapitalization described in the recitals
   hereto. The number of outstanding shares described in (i), (i), and (iii),
   when added together, totals 35,592.

3. Sections (iv), (v), (vi), and (vii) hereby are deleted in their entirety and
   shall be replaced with the following:

     (iv) 66,102 Warrant Shares upon the effective date of this Amendment.

ENTIRE AGREEMENT. Together the Warrant Agreement and this Amendment constitute
the entire agreement between the Parties in connection with the subject matter
thereof and supersede all prior and contemporaneous agreements, understandings,
negotiations and discussions, whether oral or written, of the Parties. No
provision of this Amendment may be modified or amended except expressly in a
writing signed by both parties nor shall any terms be waived except expressly in
a writing signed by the party charged therewith. This Amendment shall be
governed in accordance with the laws of the State of Delaware, without regard to
principles of conflicts of laws.

     IN WITNESS WHEREOF, the parties have executed this Amendment.

GENVEC, INC.                                   CORNELL RESEARCH FOUNDATION, INC.


By:     /s/ Thomas E. Smart                    By:    /s/ Brian Kelly
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Title:  Thomas E. Smart                        Title: Vice President
       -----------------------------                  ------------------------
        Sr. Vice President,
        Corporate Development
        GenVec, Inc.

Date:   March 18, 2002                         Date:  March 18, 2002
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