Exhibit 10.1

IDEXX LABORATORIES, INC.

DIRECTOR DEFERRED COMPENSATION PLAN

The Deferred Compensation Plan for non-employee Directors of IDEXX Laboratories,
Inc. (the “Plan”) is designed to provide an additional mechanism for satisfying
stock ownership guidelines as well as to provide a vehicle for the deferral of
taxable income. The Plan is intended to be an “unfunded” plan maintained for the
purpose of providing deferred compensation to non-employee members of the Board
of Directors for purposes of Title I of the Employee Retirement Income Security
Act of 1974.

ARTICLE I

DEFINITIONS

Unless the context otherwise requires, the following words and phrases as used
herein shall have the following meanings:

Section 1.1 “ACCOUNT BALANCE” means the total amount credited to the bookkeeping
Investment Accounts in which Contributions are maintained for a Participant,
including earnings thereon.

Section 1.2 “ANNUAL RETAINER” means the annual cash retainer paid by the Company
to Directors.

Section 1.3 “BENEFICIARY” means the person that the Participant designates to
receive any unpaid portion of the Participant’s Account Balance should the
Participant’s death occur before the Participant receives the entire Account
Balance. If the Participant does not designate a beneficiary, his Beneficiary
shall be his spouse if he is married at the time of his death, or his estate if
he is unmarried at the time of his death.

Section 1.4 “BOARD OF DIRECTORS” means the Board of Directors of IDEXX
Laboratories, Inc.

Section 1.5 “CODE” means the Internal Revenue Code of 1986, as amended.

Section 1.6 “COMPANY” means the IDEXX Laboratories, Inc. and any subsidiary
designated by the Plan Administrator.

Section 1.7 “COMPENSATION” means any cash remuneration paid to or earned by a
Participant.

Section 1.8 “CONTRIBUTIONS” means amounts deferred under the Plan pursuant to
Article III and allocated to a Participant’s Investment Accounts. No money or
other assets will actually be contributed to such Investment Accounts.

Section 1.9 “DIRECTOR” means a non-employee member of the Board of Directors.

Section 1.10 “EFFECTIVE DATE” means July 1, 2003.

Section 1.11 “IDEXX STOCK” means Common Stock of IDEXX Laboratories, Inc.

Section 1.12 “IDEXX STOCK INVESTMENT ACCOUNT” means an Investment Account in
which deferred amounts are valued as if they were invested in IDEXX Stock.

Section 1.13 “INVESTMENT ACCOUNT” means a book accounting record, maintained for
each Participant, valued in accordance with the performance of the investment
choice in which the deferred amounts are notionally invested. No funds are
actually contributed to an Investment Account and there are no assets in any
Investment Account.

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Section 1.14 “MANDATORY DEFERRAL” means the deferral of a Director’s Annual
Retainer as described in Section 3.2.

Section 1.15 “PARTICIPANT” means a Director who participates in the Plan.

Section 1.16 “PLAN” means this Deferred Compensation Plan, as it may be amended
from time to time.

Section 1.17 “PLAN ADMINISTRATOR” means the Vice President — Human Resources of
IDEXX Laboratories, Inc. or any person or entity designated by the Vice
President — Human Resources.

Section 1.18 “PLAN YEAR” means the 12-month period beginning January 1 and
ending December 31. The initial plan year will be a short plan year, commencing
July 1, 2003 and ending December 31, 2003.

ARTICLE II

ELIGIBILITY AND PARTICIPATION

Section 2.1 ELIGIBILITY. Each Director shall be immediately eligible to become a
Participant in the Plan.

Section 2.2 PARTICIPATION. Each Director shall become a Participant in the Plan
immediately upon election to the Board by the method required by the Plan
Administrator. Each Director shall remain a Participant under the Plan until all
amounts credited to the Participant’s Account Balance have been distributed to
the Participant or the Participant’s Beneficiary.

ARTICLE III

CONTRIBUTIONS

Section 3.1 GENERAL

(a)     Any Participant may, by delivering a written election to the Plan
Administrator by the Effective Date, elect to defer receipt of up to 100% of his
or her Compensation for the portion of 2003 following the Effective Date. Any
Participant may, by delivering a written election to the Plan Administrator on
or before November 30 of 2003 and each year thereafter, elect to defer receipt
of up to 100% of his or her Compensation during the calendar year following such
election. The Plan Administrator will determine which investment alternatives
will be available for this purpose. The Company shall contribute an amount equal
to that portion of Compensation that the Participant has elected to defer under
the Plan to the applicable Investment Accounts.

(b)     Any person who shall become a Participant during any calendar year
following the time specified for making the deferral election for such year as
provided in 3.1(a) above, may, within 15 days of the beginning of his or her
term, elect to defer receipt of all or a specified part of his or her
Compensation during the balance of such calendar year and for succeeding
calendar years.

(c)     Any such election shall be in writing and shall be delivered to the Plan
Administrator.

(d)     A Participant’s election to defer receipt of Compensation shall continue
until the date on which such Participant ceases to be a Director or, with the
exception of the Mandatory Deferral, until he or she terminates such election by
written notice delivered to the Plan Administrator. Any such notice terminating
an election to defer compensation shall be effective as of the end of the
calendar year in which such notice of termination is delivered.

Section 3.2 MANDATORY DEFERRAL. Each Participant shall be required to defer 50%
of his or her Annual Retainer in the form of IDEXX Stock deferred stock units
and to have the Company make an equivalent contribution of that amount to his or
her IDEXX Stock Investment Account.

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ARTICLE IV

INVESTMENT ACCOUNTS AND DISTRIBUTIONS

Section 4.1 INVESTMENT ACCOUNTS. The Plan Administrator shall designate the
Investment Accounts that will be available to Participants under the Plan. The
Plan Administrator shall also designate how often and what procedures must be
followed to reallocate amounts in the Investment Accounts.

Section 4.2 DISTRIBUTIONS. One year from the termination of a Participant’s
Board membership for any reason, the Participant will receive shares of IDEXX
Stock equal to the number of notional shares in his or her IDEXX Stock
Investment Account.

ARTICLE V

ADMINISTRATIVE PROCEDURES

Section 5.1 GENERAL. The Plan shall be administered by the Plan Administrator.
The Plan Administrator shall establish such procedures and rules as he or she,
in his or her sole discretion, shall deem appropriate regarding the timing of
deferral elections, the time period for deferral, the forms of distribution, the
maximum number of annual installment payments, the Investment Accounts for
valuing Account Balances, reallocation of Account Balances among Investment
Accounts, statements of Account Balances, the time and manner of payment of
Account Balances, and other administrative items for this Plan.

Section 5.2 PLAN INTERPRETATION. The Plan Administrator shall have the authority
and responsibility to interpret and construe the Plan and to decide all
questions arising thereunder, including without limitation, questions of
eligibility for participation, eligibility for Contributions, the amount of
Account Balances, and the timing of the distribution thereof, and shall have the
authority to deviate from the literal terms of the Plan to the extent the Plan
Administrator shall determine, in his or her sole discretion, to be necessary or
appropriate to operate the Plan in compliance with the provisions of applicable
law.

Section 5.3 RESPONSIBILITIES AND REPORTS. The Plan Administrator may pursuant to
a written instruction name other persons to carry out specific responsibilities.
The Plan Administrator shall be entitled to rely conclusively upon all tables,
valuations, certificates, opinions and reports that are furnished by any
accountant, controller, counsel, or other person who is employed or engaged for
such purposes.

ARTICLE VI

CLAIMS PROCEDURE

Section 6.1 DENIAL OF CLAIM FOR BENEFITS. Any denial by the Plan Administrator
of any claim for benefits under the Plan by a Participant or Beneficiary shall
be stated in writing by the Plan Administrator and delivered or mailed to the
Participant or Beneficiary. The Plan Administrator shall furnish the claimant
with notice of the decision not later than 90 days after receipt of the claim,
unless special circumstances require an extension of time for processing the
claim. If such an extension of time for processing is required, written notice
of the extension shall be furnished to the claimant prior to the termination of
the initial 90-day period. In no event shall such extension exceed a period of
90 days from the end of such initial period. The extension notice shall indicate
the special circumstances requiring an extension of time and the date by which
the Plan Administrator expects to render the final decision. The notice of the
Plan Administrator’s decision shall be written in a manner calculated to be
understood by the claimant and shall include (i) the specific reasons for the
denial, including, where appropriate, references to the Plan, (ii) any
additional information necessary to perfect the claim with an explanation of why
the information is necessary, and (iii) an explanation of the procedure for
perfecting the claim.

Section 6.2 APPEAL OF DENIAL. The claimant shall have 60 days after receipt of
written notification of denial of his or her claim in which to file a written
appeal with the Plan Administrator. As a part of any such appeal, the

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claimant may submit issues and comments in writing and shall, on request, be
afforded an opportunity to review any documents pertinent to the perfection of
his or her claim. The Plan Administrator shall render a written decision on the
claimant’s appeal ordinarily within 60 days of receipt of notice thereof but, in
no case, later than 120 days.

ARTICLE VII

FUNDING

Section 7.1 FUNDING. The Company shall not segregate or hold separately from its
general assets any amounts credited to the Investment Accounts for Participants,
and shall be under no obligation whatsoever to fund in advance any amounts under
the Plan, including Contributions and earnings thereon.

Section 7.2 INSOLVENCY. In the event that the Company becomes insolvent, all
Participants and Beneficiaries shall be treated as general, unsecured creditors
of the Company with respect to any amounts credited to the Investment Accounts.

ARTICLE VIII

AMENDMENT AND TERMINATION

Section 8.1 The Company reserves the right to amend or terminate the Plan at any
time by action of the Board or the Compensation Committee thereof.
Notwithstanding the foregoing, no such amendment or termination shall reduce any
Participant’s Account Balance as of the date of such amendment or termination.
Upon a complete termination of the Plan, all vested Account Balances may be
immediately distributed or may be paid out in accordance with Participant’s
deferral elections at the discretion of the Plan Administrator.

ARTICLE IX

CHANGE IN CONTROL

Section 9.1 PROVISIONS. Notwithstanding anything contained in the Plan to the
contrary, the provisions of this Article IX shall govern and supersede any
inconsistent terms or provisions of the Plan.

Section 9.2 DEFINITION OF CHANGE IN CONTROL. For purposes of the Plan “Change in
Control” shall mean the happening of any of the following events:

    (i)        an acquisition by any individual, entity or group (within the
meaning of Section 13(d)(3) or 14(d)(2) of the Securities Exchange Act of 1934
(the “Exchange Act”)) (an “Entity”) of beneficial ownership (within the meaning
of Rule 13d-3 promulgated under the Exchange Act) of 30% or more of either
(A) the then outstanding shares of IDEXX Stock (the “Outstanding Company Common
Stock”) or (B) the combined voting power of the then outstanding voting
securities of the Company entitled to vote generally in the election of
directors (the “Outstanding Company Voting Securities”); excluding, however, the
following: (1) any acquisition directly from the Company, other than an
acquisition by virtue of the exercise of a conversion privilege unless the
security being so converted was itself acquired directly from the Company, (2)
any acquisition by the Company, (3) any acquisition by any employee benefit plan
(or related trust) sponsored or maintained by the Company or any corporation
controlled by the Company, or (4) any acquisition by any corporation pursuant to
a transaction that complies with clauses (A), (B) and (C) of Section 9.2(iii);

    (ii)        a change in the composition of the Board on the Plan’s effective
date such that the individuals who, as of the effective date, constitute the
Board (such Board shall be hereinafter referred to as the “Incumbent Board”)
cease for any reason to constitute at least a majority of the Board; provided,
however, that for purposes of this definition, any individual who becomes a
member of the Board subsequent to the effective date, whose election, or
nomination for election, by the Company’s stockholders was approved by a vote of
at least a majority of those individuals who are members of the Board and who
were also members of the Incumbent Board (or deemed to be such pursuant to this
proviso) shall be considered as though such individual were a member of the
Incumbent Board; and provided further, however, that any such individual whose
initial assumption

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of office occurs as a result of or in connection with either an actual or
threatened solicitation with respect to the election of directors (as such terms
are used in Rule 14a-12(c) of Regulation 14A promulgated under the Exchange Act)
or other actual or threatened solicitation of proxies or consents by or on
behalf of an Entity other than the Board shall not be so considered as a member
of the Incumbent Board;

    (iii)        the consummation of a merger, reorganization or consolidation
or sale or other disposition of all or substantially all of the assets of the
Company (each, a “Corporate Transaction”), excluding however, any Corporate
Transaction pursuant to which (A) all or substantially all of the individuals
and entities who are the beneficial owners, respectively, of the Outstanding
Company Common Stock and Outstanding Company Voting Securities immediately prior
to such Corporate Transaction will beneficially own, directly or indirectly,
more than 60% of, respectively, the outstanding shares of common stock, and the
combined voting power of the then outstanding voting securities entitled to vote
generally in the election of directors, as the case may be, of the corporation
resulting from such Corporate Transaction (including, without limitation, a
corporation or other person that as a result of such transaction owns the
Company or all or substantially all of the Company’s assets either directly or
through one or more subsidiaries (a “Parent Company”)) in substantially the same
proportions as their ownership, immediately prior to such Corporate Transaction,
of the Outstanding Company Common Stock and Outstanding Company Voting
Securities, as the case may be, (B) no Entity (other than the Company, any
employee benefit plan (or related trust) of the Company, such corporation
resulting from such Corporate Transaction or, if reference was made to equity
ownership of any Parent Company for purposes of determining whether clause (A)
above is satisfied in connection with the applicable Corporate Transaction, such
Parent Company) will beneficially own, directly or indirectly, 30% or more of,
respectively, the outstanding shares of common stock of the corporation
resulting from such Corporate Transaction or the combined voting power of the
outstanding voting securities of such corporation entitled to vote generally in
the election of directors unless such ownership resulted solely from ownership
of securities of the Company prior to the Corporate Transaction, and
(C) individuals who were members of the Incumbent Board will immediately after
the consummation of the Corporate Transaction constitute at least half of the
members of the board of directors of the corporation resulting from such
Corporate Transaction (or, if reference was made to equity ownership of any
Parent Company for purposes of determining whether clause (A) above is satisfied
in connection with the applicable Corporate Transaction, of the Parent Company);
or

    (iv)        the approval by stockholders of the Company of a complete
liquidation or dissolution of the Company.

Section 9.3 IMPACT OF CHANGE IN CONTROL. Upon a Change in Control, (i) the
Account Balances of each Participant shall vest in full and any applicable
deferral limitations or other restrictions shall lapse, (ii) Account Balances in
any IDEXX Stock Investment Account will be distributed, and the shares of IDEXX
Stock so distributed shall be deemed to have been outstanding immediately prior
to such Change in Control, and (iii) Account Balances in any other Investment
Accounts shall be valued as of the date of the Change in Control and shall be
distributed to each Participant.

ARTICLE X

MISCELLANEOUS

Section 10.1 NO EMPLOYMENT CONTRACT. The establishment or existence of the Plan
shall not confer upon any individual the right to be continued as a Director.

Section 10.2 NON-ALIENATION. No amounts payable under the Plan shall be subject
in any manner to anticipation, assignment, or voluntary or involuntary
alienation.

Section 10.3 GOVERNING LAW. The Plan shall be governed by and construed in
accordance with the laws of the State of Maine to the extent not preempted by
federal law.

Section 10.4 WITHHOLDING. The Company shall withhold from any benefits payable
under the Plan all federal, state and local income taxes or other taxes required
to be withheld pursuant to applicable law.

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Section 10.5 INCAPACITY. If the Plan Administrator, in his or her sole
discretion, deems a Participant or Beneficiary who is eligible to receive any
payment hereunder to be incompetent to receive the same by reason of illness or
any infirmity or incapacity of any kind, the Plan Administrator may direct the
Company to apply such payment directly for the benefit of such person, or to
make payment to any person selected by the Plan Administrator to disburse the
same for the benefit of the Participant or Beneficiary. Payments made pursuant
to this Section shall operate as a discharge, to the extent thereof, of all
liabilities of the Company, the Plan Administrator and the Plan to the person
for whose benefit the payments are made.

Section 10.6 CONSTRUCTION OF TERMS. For purposes of the Plan, the singular shall
include the plural, and vice versa and the masculine shall include the feminine.

Section 10.7 BINDING UPON SUCCESSORS. The liabilities under the Plan shall be
binding upon any successor, assign or purchaser of the Company or any purchaser
of substantially all of the assets of the Company.

Section 10.8 TRUST ARRANGEMENT. All benefits under the Plan represent an
unsecured promise to pay by the Company. The Plan shall be unfunded and the
benefits hereunder shall be paid only from the general assets of the Company
resulting in the Participants having no greater rights than the Company’s other
general creditors. Nothing herein shall prevent or prohibit the Company from
establishing a trust or other arrangement for the purpose of providing for the
payment of the benefits payable under the Plan.

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