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                                                                    EXHIBIT 10.8


[MEGABIOS CORP. LOGO]                                    BENJAMIN F. MCGRAW, III
                                                       Chairman, President & CEO


18 May, 1998


Bennet L. Weintraub
3012 Hillside Drive
Burlingame, CA 94010

Dear Bennet:

This letter is an offer from Megabios Corp. (the "Company") to you for the 
position of Vice President and Chief Financial Officer reporting to me. The 
offer consists of the following:

1.   Annual salary of $170,000.

2.   Eligibility for any Bonus Program applicable to officers of the Company.

3.   Incentive stock option grant: 80,000 options, each entitling you to 
     purchase one share of the Company's common stock. The exercise price of 
     this option is set by the Board of Directors based on the price at which 
     equity trades on NASDAQ on the date of Board approval. The option will 
     vest over a four-year period beginning with the effective date of your 
     employment.

4.   The Company will loan you $160,000 for the purpose of exercising 
     Megabios Corp. stock options.

5.   Contingent on your achieving certain performance criteria established by 
     the Company, you will be eligible to receive up to an aggregate of 
     $70,000 in bonus compensation payable in such amounts and at such times 
     as the Compensation Committee may designate over your first four years 
     of employment with the Company. Such bonus shall be in addition to any 
     bonus for which you will become eligible under any Bonus Program 
     generally applicable to officers of the Company.

6.   You will be enrolled in the Company's corporate health care plan and are 
     entitled to all the corporate benefits for a Vice President level 
     position.

7.   The Company will provide you time off without pay during the period from 
     June 8 through June 19.

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8.   The effective date of your employment will be no later than May 26, 
     1998. This offer will remain in effect until May 25, 1998. Please 
     acknowledge your acceptance by signing below and returning this letter 
     to Michael Coyne.

9.   You acknowledge that your employment relationship with the Company is 
     based on the mutual consent of the employee and the Company. This means 
     that you may resign your employment with the Company at any time. 
     Similarly, the Company may terminate your employment at any time and for 
     any reason whatsoever, with or without cause or advance notice. This 
     at-will employment relationship cannot be changed except in writing 
     signed by a Company officer.

10.  You acknowledge that this letter constitutes the complete, final, and 
     exclusive embodiment of the entire agreement between you and the Company 
     with regard to your employment at Megabios Corp. It is entered into 
     without reliance on any promise or representation, written or oral, 
     other than those expressly contained herein, and it supersedes any other 
     such promises, warranties or representations. This offer letter of 
     employment may not be modified or amended except in writing signed by 
     both you and a duly authorized officer of the Company.

Bennett, we are very excited about working with you. Should you have any 
questions about any part of this offer, please do not hesitate to discuss 
them with me.

Sincerely                               Accepted:

/s/  Benjamin F. McGraw, III            /s/  Bennet L. Weintraub
                                        -------------------------------------
Benjamin F. McGraw, III                 Bennet L. Weintraub
Chairman, President & CEO