Prepared by MERRILL CORPORATION





Exhibit 10.12


Effective as of May 15, 2001


Mr. Walter Ogier

433 Main Street

Winchester, MA  01890


Dear Walter:


I am writing to confirm our offer to you
for a position as President and Chief Operating Officer, reporting to Elliot
Lebowitz, Ph.D., Chief Executive Officer. 
We are pleased to offer you a starting salary of $20,130.00 per month
(equivalent to $241,560.00 per year), to be paid semi-monthly and reviewed
annually.  The monthly salary includes
an allowance to help offset contributions to certain benefits should you elect
them.  You are also eligible for an
annual cash bonus of 35% of base salary and to participate in our annual
merit-based stock option program, provided that any award of options will be
subject to the approval of our Board of Directors. You are also entitled to
receive shares of BTI common stock in accordance with the terms and conditions
of the Eligix, Inc. Management Equity Incentive Plan. In addition, you will
receive medical and dental insurance, 15% of the cost of which is contributed
by the employee.  Term life insurance,
equivalent to one times your annual salary, and parking will be provided by the
company without employee contribution. Long-term disability insurance is
provided, 100% of the cost is contributed by the employee (your annual premium
would be approximately $1,416.00).  You
will also be entitled to three weeks paid vacation accrued on an annual basis
and 11 paid holidays per year.  In the
event your employment is terminated by Biotransplant without cause, you would receive
up to 12 months double base salary, payable in 24 equal semi-monthly
installments, which would be discontinued upon your securing other employment.


Your employment is subject to your
signing an Invention, Non-Disclosure and Non-Compete Agreement with
BioTransplant, in the form previously provided to you, and review of any
agreement you may have with others to insure that your employment with
BioTransplant is not in conflict with any such agreements.


Also, this offer is contingent upon your
ability to provide proof of your legal right to work in the United States, as
defined by Federal regulations.


By signing this letter below, you
acknowledge that the foregoing offered terms of your employment with
BioTransplant do not constitute (i) a significant diminution of your duties,
responsibilities, power, title or office in effect at Eligix, Inc. immediately
prior to your acceptance of this offer or (ii) a material reduction in your
compensation (including without limitation, salary, bonuses, options and benefits)
or material change in your manner of compensation (including without
limitation, the timing of any salary or bonus payments) in effect for you at
Eligix, Inc. immediately prior to your acceptance of this offer.


If you agree to the terms outlined above,
please sign both copies of this letter and return one copy using the enclosed,
stamped envelope.





We look forward to your joining
BioTransplant. We are confident that you will make a significant contribution
to BioTransplant's future success.


Sincerely,


/s/ Elliot Lebowitz

Elliot Lebowitz, Ph.D.

President and CEO


Accepted and Agreed to:


	/s/
  Walter C. Ogier	 	 
	

	 	 
	Name:  Walter C. Ogier	 	Date:  May 15, 2001