Document:

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                                                           EXHIBIT 10.21

                                   [Logo]

April 13, 1999

Henrik S. Rasmussen, M.D., Ph.D.
628 Magothy View Drive
Arnold, MD 21012

Dear Dr. Rasmussen:

It is with great pleasure that we extend an offer of employment to you for
the position of Vice President, Clinical Operations & Regulatory Affairs. We
were all very impressed with your background and experience and we believe
that you would be a valuable addition to the GenVec team. You will report to
Paul Fischer, President and CEO.

The specific terms of this offer are detailed in the enclosed schedule. As
discussed, your start date is on May 1, 1999. Two copies of the GenVec
Confidentiality, Invention and Non-Compete Agreement that must be signed by
each GenVec employee are enclosed.

If the terms of this offer are acceptable to you, please sign and date both
copies of the enclosed schedule and the GenVec Confidentiality, Invention,
and Non-Compete Agreement, keep one of each for yourself and return the other
to me.

This letter and schedule, along with the GenVec Confidentiality, Invention
and Non-Compete Agreement, set forth the terms of your employment with GenVec
and supersedes any prior representations or agreements, whether written or
oral. This agreement may not be modified or amended except by a written
agreement, signed by an officer of GenVec and by you.

Sincerely,

/s/ Paul H. Fischer, Ph.D.
Paul H. Fischer, Ph.D.
President and CEO

enc.

<PAGE>

                                GenVec, Inc.
                        Terms of At-Will Employment

Employee Name:    Henrik S. Rasmussen, M.D., Ph.D.

Position:         Vice President, Clinical Operations & Regulatory Affairs

Start Date:       May 1, 1999

Salary:           $190,000 per year, to be paid in semi-monthly installments

Sign-On Bonus:    Upon receipt of signed employment letter and
                  confidentiality agreement, a sign-on bonus of $20,000 will
                  be paid to Dr. Rasmussen.

Bonus:            Eligible for bonus based on achievement of corporate and
                  individual objectives. Distribution of bonus is in
                  accordance with the approved 1999 GenVec Compensation PLan.

Equity:           A new hire grant of stock options to purchase 75,000 shares
                  of Common Stock at a strike price equal to the fair market
                  value as determined by the Board of Directors as of the
                  date of grant. Such options will be issued under and
                  subject to the terms and conditions of the Company's
                  Amended and Restated 1993 Stock Option Plan and will begin
                  vesting as of date of hire.

Salary
Continuation:     Should employment be terminated for any reason other than
                  for cause, salary would continue to be paid for a period of
                  six (6) months from the effective date of such termination.
                  Payments made thereunder would cease if permanent
                  employment is found at the same or greater salary during
                  the 6-month period.

                  "For cause" shall include: employee's gross negligence in
                  the performance of his/her duties, intentional
                  nonperformance or misperformance of such duties
                  or refusal to abide by or comply with the directives of the
                  Board of Directors, his/her superior officers, or GenVec's
                  policies and procedures, which actions continue for a
                  period of at least 10 days after receipt by employee of
                  written notice of the need to cure or cease.

Benefits:         Four (4) weeks vacation to accrue at a rate of 6.67 hours
                  per semi-monthly pay period commencing with the hire date.

                  Holidays, as set forth in the company's holiday schedule as
                  well as two (2) personal days, allocated and defined in the
                  Employee Handbook.

<PAGE>

                  Health Insurance - Health/dental insurance is provided by
                  American Medial Security Health Insurance Company. This is
                  a PPO system. GenVec covers 80% of the premium costs for
                  each employee.

                  Disability - Short term and long term disability provided.

                  Life Insurance - GenVec covers the cost of life insurance
                  to a maximum of $50,000 payout of beneficiaries.

                  Section 125 Plan - GenVec provides for pre-tax withdrawal
                  of employee's salary to cover costs for items such as
                  medical insurance premiums, medical reimbursement and
                  licensed dependent care.

                  Tuition reimbursement - After 90 days of employment and
                  approval from the employee's manager, GenVec will reimburse
                  the employee for approved courses in accordance with terms
                  listed in the Employee Handbook.

                  401(k) Plan - After six (6) months of employment and at the
                  open enrollment period, an employee, age 21 years or
                  greater is eligible to participate in GenVec's 401(k) Plan.
                  Employee contribution is limited to 15% of base salary or
                  to a maximum of $10,000 per year, per Federal law.

At-Will
Employment:       You should be aware that your employment with GenVec is for
                  no specified period and constitutes at-will employment. As
                  a result, you are free to resign at any time, for any
                  reason or for no reason. Similarly, GenVec is free to
                  conclude its employment relationship with you at any time,
                  with or without cause, and with or without notice.

Agreed to and Accepted By:

/s/ Henrik S. Rasmussen, M.D., Ph.D.        April 15, 1999
------------------------------------        ---------------------------
Henrik S. Rasmussen, M.D., Ph.D.            Date<PAGE>

                                                                EXHIBIT 10.22

April 8, 1998

C. Richter King, Ph.D.
1840 Park Road
Washington, DC 20010

Dear Rick:

It is with great pleasure that we extend an offer of employment to you for
the position of Vice President, New Product Research. We were all very
impressed with your background and experience and we believe that you would
be a valuable addition to the GenVec team. You will report to Paul Fischer,
President and CEO.

The specific terms of this offer are detailed in the enclosed schedule. As
discussed, your start date is on May 1, 1998. Two copies of the GenVec
Confidentiality, Invention and Non-Compete Agreement that must be signed by
each GenVec employee are enclosed.

If the terms of this offer are acceptable to you, please sign and date both
copies of the enclosed schedule and the GenVec Confidentiality, Invention,
and Non-Compete Agreement, keep one of each for yourself and return the other
to me.

This letter and schedule, along with GenVec Confidentiality, Invention and
Non-Compete Agreement, set forth the terms of your employment with GenVec and
supersedes any prior representations or agreements, whether written or oral.
This agreement may not be modified or amended except by a written agreement,
signed by an officer of GenVec and by you.

Sincerely,

/s/ Paul H. Fischer, Ph.D.
Paul H. Fischer, Ph.D.
President and CEO

enc.

<PAGE>

                                 GenVec, Inc.
                        Terms of At-Will Employment

Employee Name:   C. Richter King, Jr.

Position:        Vice President, New Product Research

Start Date:      Effective date of hire is April 15, 1998. Should Dr. King's
                 services be required prior to the full-time start date, he
                 will be paid at a daily rate of $577 (based on pro-ration of
                 base salary).

Salary:          $150,000 per year, to be paid in semi-monthly installments

Bonus:           It is anticipated that a performance bonus up to 25% may be
                 applicable.

Equity:          A new hire grant of stock options to purchase 375,00 shares
                 of Common Stock at a strike price equal to the fair market
                 value as determined by the Board of Directors as of the date
                 of grant (expected to be $1.00 per share). Such options will
                 be issued under and subject to the terms and conditions of
                 the Company's Amended and Restated 1993 Stock Option Plan
                 and will begin vesting as of the date of hire. As has been
                 discussed during employment negotiations, a reverse split of
                 these options will occur upon initial public offering (IPO).

Salary
Continuation:    Should employment be terminated for any reason other than
                 for cause, salary would continue to be paid for a period of
                 six (6) months from the effective date of such termination.
                 Payments made thereunder would cease if permanent employment
                 is found at the same or greater salary during the 6-month
                 period.

                 "For cause" shall include: employee's gross negligence in
                 the performance of his/her duties, intentional nonperformance
                 or misperformance of such duties or refusal to abide by or
                 comply with the directives of the Board of Directors,
                 his/her superior officers, or GenVec's policies and
                 procedures, which actions continue for a period of at least
                 10 days after receipt by employee of written notice of the
                 need to cure or cease.

Benefits:        Three (3) weeks vacation to accrue at a rate of five (5)
                 hours per semi-monthly pay period commencing with the hire
                 date.

                 Holidays, as set forth in the company's holiday schedule as
                 well as two (2) personal days, allocated and defined in the
                 Employee Handbook.

                 Health Insurance - Health/dental insurance is provided by
                 American Medical Security Health Insurance Company. This is
                 a PPO system. GenVec covers 80% of the premium cost for each
                 employee.

<PAGE>

                 Disability - Short term and long term disability provided

                 Life Insurance - GenVec covers the cost of life insurance to
                 a maximum of $50,000 payout to beneficiaries.

                 Section 125 Plan - GenVec provides for pre-tax withdrawal of
                 employee's salary to cover costs for items such as medical
                 insurance premiums, medical reimbursement and licensed
                 dependent care.

                 Tuition reimbursement - After 90 days of employment and
                 approval from the employee's manager, GenVec will reimburse
                 the employee for approved courses in accordance with terms
                 listed in the Employee Handbook.

                 401(k) Plan - After six (6) months of employment and at the
                 open enrollment period, an employee, age 21 years or greater
                 is eligible to participate in GenVec's 401(k) Plan. Employee
                 contribution is limited to 15% of base salary or to a
                 maximum of $10,000 per year, per Federal law.

At-Will
Employment:      You should be aware that your employment with GenVec is for
                 no specified period and constitutes at-will employment. As a
                 result, you are free to resign at any time, for any reason
                 or for no reason. Similarly, GenVec is free to conclude its
                 employment relationship with you at any time, with or
                 without cause, and with or without notice.

Agreed to and Accepted By:

/s/ C. Richter King. Ph.D.                     April 15, 1998
---------------------------------      -----------------------------
C. Richter King. Ph.D.                              Date

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