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                                                                    EXHIBIT 10.1

                                    AGREEMENT

This Agreement is entered into by IDEXX Laboratories, Inc. ("IDEXX") and David
E. Shaw ("Shaw") regarding Shaw's reappointment as Chief Executive Officer of
IDEXX, and the planned recruitment and appointment of a person to succeed Shaw
as such Chief Executive Officer. In consideration of Shaw's willingness to serve
as Chief Executive Officer pending the identification and appointment of a
successor (the "Succession"), and to serve as Executive Chairman for a period of
time after the Succession, and for other good and valuable consideration, the
parties agree as follows:

1.   From the date hereof until the date of the Succession (the "CEO Term"),
     Shaw agrees to serve, and IDEXX agrees to retain Shaw, as Chief Executive
     Officer, unless Shaw voluntarily resigns prior to expiration of the CEO
     Term. During the CEO Term, Shaw will perform responsibilities consistent
     with his position as Chief Executive Officer, and will assist in the
     recruitment of a successor.

2.   If requested by the Board of Directors in connection with and prior to the
     Succession, until December 31, 2001, or such later date as may be mutually
     agreed upon (such period, the "Executive Chairman Term" and together with
     the CEO Term, the "Term"), Shaw agrees to serve as a part time employee of
     IDEXX with the title of "Executive Chairman" unless Shaw voluntarily
     resigns prior to expiration of the Term. During the Executive Chairman
     Term, Shaw will perform responsibilities consistent with his position as
     Executive Chairman, as mutually agreed with the Board of Directors.

3.   Shaw's annual base salary during the Term shall initially be $400,000, and
     will be subject to change during the Term by mutual agreement. Eligibility
     for cash bonuses or stock option grants will be at the discretion of
     IDEXX's Board of Directors but consistent with senior officer guidelines.
     During the Term, Shaw will participate at current levels in IDEXX benefit
     programs including on-site or off-site administrative support and office
     facilities.

4.   If Shaw's employment is terminated during the Term, by IDEXX, or by Shaw as
     a result of breach by IDEXX of this Agreement, then Shaw shall have all the
     rights and IDEXX shall have all the obligations provided for in the
     Employment Agreement referred to in paragraph 5 below upon a termination of
     the Executive's employment thereunder for Good Reason during the Employment
     Period. For this purpose a Change of Control will be deemed to have
     occurred on the date of termination, and the provisions of the "parachute",
     including immediate vesting of all stock options, will become effective.
     Additionally, for this purpose, if Shaw shall not be Chief Executive
     Officer at the time of such termination, "Annual Base Salary" shall mean
     Shaw's annual base salary as Chief Executive Officer.

5.   This Agreement supersedes in its entirety the Agreement dated February 17,
     1999 between IDEXX and Shaw. The Employment Agreement dated April 25, 1997
     between Shaw and IDEXX will remain in effect and, in the event of any
     conflict or inconsistency between this Agreement and such Employment
     Agreement at or after the Effective Date of the Employment Agreement, the
     Employment Agreement shall control.

Agreed to as of August 26, 1999

For IDEXX Laboratories, Inc.:


By:  /s/ James L. Moody                        /s/ David E. Shaw
     --------------------------------          ---------------------------------
     James L. Moody, Jr., Chairman             David E. Shaw
     Compensation Committee