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                                                                     Exhibit 4.1


           THIS WARRANT AND THE SHARES OF COMMON STOCK ISSUED UPON ITS
                   EXERCISE ARE SUBJECT TO THE RESTRICTIONS ON
                 TRANSFER SET FORTH IN SECTION 5 OF THIS WARRANT


Date of Issuance: October 1, 1998                      Number of Shares:________
                                                         (subject to adjustment)


                            IDEXX LABORATORIES, INC.

                          Common Stock Purchase Warrant

                         (Void after September 30, 2003)


         IDEXX Laboratories, Inc., a Delaware corporation (the "Company"), for
value received, hereby certifies that ______________________ (the "Registered
Holder") is entitled, subject to the terms set forth below, to purchase from the
Company, at any time or from time to time on or after the date of issuance and
on or before September 30, 2003 (the "Expiration Date") at not later than 5:00
p.m. (Portland, Maine time), ________ shares of Common Stock, $.10 par value per
share, of the Company, at a purchase price of $31.59 per share. The shares
purchasable upon exercise of this Warrant, and the purchase price per share,
each as adjusted from time to time pursuant to the provisions of this Warrant,
are hereinafter referred to as the "Warrant Shares" and the "Purchase Price,"
respectively.

         1. Vesting Schedule. This Warrant will become exercisable on the date
six months after the date of this Warrant.

         2. Exercise.

                  (a) This Warrant may be exercised by the Registered Holder, in
whole or in part, by surrendering this Warrant, with the purchase form appended
hereto as Exhibit I duly executed by the Registered Holder or by the Registered
Holder's duly authorized attorney, at the principal office of the Company, or at
such other office or agency as the Company may designate, accompanied by payment
in full, in lawful money of the United States, of the Purchase Price payable in
respect of the number of Warrant Shares purchased upon such exercise.

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                  (b) The Registered Holder may, at its option, elect to pay
some or all of the Purchase Price payable upon an exercise of this Warrant by
cancelling a portion of this Warrant exercisable for such number of Warrant
Shares as is determined by dividing (i) the total Purchase Price payable in
respect of the number of Warrant Shares being purchased upon such exercise by
(ii) the excess of the Fair Market Value per share of Common Stock as of the
effective date of exercise, as determined pursuant to subsection 2(b) below (the
"Exercise Date") over the Purchase Price per share. If the Registered Holder
wishes to exercise this Warrant pursuant to the preceding sentence with respect
to the maximum number of Warrant Shares purchasable pursuant to this method,
then the number of Warrant Shares so purchasable shall be equal to the total
number of Warrant Shares, minus the product obtained by multiplying (x) the
total number of Warrant Shares by (y) a fraction, the numerator of which shall
be the Purchase Price per share and the denominator of which shall be the Fair
Market Value per share of Common Stock as of the Exercise Date. The Fair Market
Value per share of Common Stock shall be determined as follows:

                           (i) If the Common Stock is listed on a national
securities exchange, the Nasdaq National Market or another nationally recognized
exchange or trading system as of the Exercise Date, the Fair Market Value per
share of Common Stock shall be deemed to be the last reported sale price per
share of Common Stock thereon on the day immediately preceding the Exercise
Date; or, if no such price is reported on such date, such price on the next
preceding business day (provided that if no such price is reported on the next
preceding business day, the Fair Market Value per share of Common Stock shall be
determined pursuant to clause (ii)).

                           (ii) If the Common Stock is not listed on a national
securities exchange, the Nasdaq National Market or another nationally recognized
exchange or trading system as of the Exercise Date, the Fair Market Value per
share of Common Stock shall be deemed to be the amount determined by the Board
of Directors to represent the fair market value per share of the Common Stock;
and, upon request of the Registered Holder, the Board of Directors (or a
representative thereof) shall promptly make such a determination and notify the
Registered Holder of the Fair Market Value per share of Common Stock.

                  (c) Each exercise of this Warrant shall be deemed to have been
effected immediately prior to the close of business on the day on which this
Warrant shall have been surrendered to the Company as provided in subsection
2(a) above. At such time, the person or persons in whose name or names any
certificates for Warrant Shares shall be issuable upon such exercise as provided
in subsection 2(d) below shall be deemed to 

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have become the holder or holders of record of the Warrant Shares represented by
such certificates.

                  (d) As soon as practicable after the exercise of this Warrant
in full or in part, the Company, at its expense, will cause to be issued in the
name of, and delivered to, the Registered Holder, or as such Holder may direct
(it being understood that such issuance shall be made without charge to the
Registered Holder for any issuance tax or other cost incurred by the Company in
connection with such exercise and issuance, excluding any applicable transfer
taxes):

                           (i) a certificate or certificates for the number of
full Warrant Shares to which the Registered Holder shall be entitled upon such
exercise plus, in lieu of any fractional share to which the Registered Holder
would otherwise be entitled, cash in an amount determined pursuant to Section 4
hereof; and

                           (ii) in case such exercise is in part only, a new
warrant or warrants (dated the date hereof) of like tenor, calling in the
aggregate on the face or faces thereof for the number of Warrant Shares equal
(without giving effect to any adjustment therein) to the number of such shares
called for on the face of this Warrant minus the sum of (a) the number of such
shares purchased by the Registered Holder upon such exercise plus (b) the number
of Warrant Shares (if any) covered by the portion of this Warrant cancelled in
payment of the Purchase Price payable upon such exercise pursuant to subsection
2(b) above.

         3.       Adjustments.

                  (a) If the outstanding shares of the Company's Common Stock
shall be subdivided into a greater number of shares or a dividend in Common
Stock shall be paid in respect of Common Stock, the Purchase Price in effect
immediately prior to such subdivision or at the record date of such dividend
shall be proportionately reduced. If outstanding shares of Common Stock shall be
combined into a smaller number of shares, the Purchase Price in effect
immediately prior to such combination shall be proportionately increased. When
any adjustment is required to be made in the Purchase Price, the number of
Warrant Shares purchasable upon the exercise of this Warrant shall be changed to
the number determined by dividing (i) an amount equal to the number of shares
issuable upon the exercise of this Warrant immediately prior to such adjustment,
multiplied by the Purchase Price in effect immediately prior to such adjustment,
by (ii) the Purchase Price in effect immediately after such adjustment.

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                  (b) If there shall occur any reorganization, recapitalization,
consolidation, merger or sale involving the Company in which the Common Stock is
converted into or exchanged for securities, cash or other property, then,
following any such reorganization, recapitalization, consolidation, merger or
sale, the Registered Holder of this Warrant shall have the right to receive upon
the exercise hereof the kind and amount of securities, cash or other property
which the Registered Holder would have been entitled to receive if, immediately
prior to such reorganization, recapitalization, consolidation, merger or sale,
the Registered Holder had held the number of shares of Common Stock subject to
this Warrant. Notwithstanding the foregoing sentence, if (x) there shall occur
any reorganization, recapitalization, consolidation, merger or sale involving
the Company in which the Common Stock is converted into or exchanged for
anything other than solely equity securities, and (y) the common stock of the
acquiring or surviving company is publicly traded, then, as part of any such
reorganization, recapitalization, consolidation, merger or sale, (i) the
Registered Holder of this Warrant shall have the right thereafter to receive
upon the exercise hereof such number of shares of common stock of the acquiring
or surviving company as is determined by multiplying (A) the number of shares of
Common Stock then subject to this Warrant by (B) a fraction, the numerator of
which is the Fair Market Value per share of Common Stock as of the effective
date of such transaction, as determined pursuant to subsection 2(b), and the
denominator of which is the fair market value per share of common stock of the
acquiring or surviving company as of the effective date of such transaction, as
determined in good faith by the Board of Directors of the Company (using the
principles set forth in subsection 2(b) to the extent applicable), and (ii) the
exercise price per share of common stock of the acquiring or surviving company
shall be the Exercise Price divided by the fraction referred to in clause (B)
above. In any such case, appropriate adjustment (as reasonably determined in
good faith by the Board of Directors of the Company) shall be made in the
application of the provisions set forth herein with respect to the rights and
interests thereafter of the Registered Holder of this Warrant, such that the
provisions set forth in this Section 3 (including provisions with respect to
adjustment of the Purchase Price) shall thereafter be applicable, as nearly as
is reasonably practicable, in relation to any securities, cash or other property
thereafter deliverable upon the exercise of this Warrant.

                  (c) When any adjustment is required to be made pursuant to
this Section 3, the Company shall promptly mail to the Registered Holder a
certificate setting forth such adjustment (including the kind and amount of
securities, cash or other property into which this Warrant shall be exercisable
and the Purchase Price) and a brief statement of the facts requiring such
adjustment.

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         4. Fractional Shares. The Company shall not be required upon the
exercise of this Warrant to issue any fractional shares, but shall make an
adjustment therefor in cash on the basis of the Fair Market Value per share of
Common Stock, as determined pursuant to subsection 2(b) above.

         5. Transfer Restrictions.

                  (a) This Warrant may not be sold or transferred without the
prior written consent of the Company, except in compliance with the provisions
of subsections 5(b) and 5(c) below. Any permitted transfer shall be effected by
surrendering this Warrant, along with a properly executed assignment, at the
principal office of the Company.

                  (b) This Warrant may be sold or transferred (i) in the case of
a Registered Holder which is a corporation, to a wholly owned subsidiary of such
corporation, (ii) in the case of a Registered Holder which is a partnership, to
a partner of such partnership or a retired partner of such partnership or to the
estate of any such partner or retired partner, and (iii) in the case of a
Registered Holder which is a limited liability company, to a member of such
limited liability company or a retired member of such company or to the estate
of any such member or retired member, provided that the transferee in each case
(A) is an "accredited investor" within the meaning of Rule 501(a) under the
Securities Act of 1933, as amended (the "Act"), and (B) agrees in writing to be
subject to the terms of this Section 5 to the same extent as if it were the
original Registered Holder hereunder. In addition, the original Registered
Holder may transfer, on one occasion only, this Warrant (or a portion thereof)
to any other person or entity with the prior written consent of the Company,
which consent may not be unreasonably withheld or delayed, provided that the
transferee (A) is an "accredited investor" within the meaning of Rule 501(a)
under the Act and (B) agrees in writing to be subject to the terms of this
Section 5 to the same extent as if it were the original Registered Holder
hereunder. In the event of the death or disability of the Registered Holder
prior to the Expiration Date, this Warrant shall be exercisable in accordance
with its terms by the personal representative or the estate of the Registered
Holder.

                  (c) The Warrant Shares may not be sold or transferred unless
either (i) they first shall have been registered under the Act, or (ii) the
Company first shall have been furnished with an opinion of legal counsel,
reasonably satisfactory to the Company, to the effect that such sale or transfer
is exempt from the registration requirements of the Act.

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                  (d) Each certificate representing Warrant Shares shall bear a
legend substantially in the following form:

                  "The securities represented by this certificate have not been
         registered under the Securities Act of 1933, as amended, and may not be
         offered, sold or otherwise transferred unless and until such securities
         are registered under such Act or an opinion of counsel satisfactory to
         the Company is obtained to the effect that such registration is not
         required."

The foregoing legend shall be removed from the certificates representing any
Warrant Shares, at the request of the holder thereof, at such time as they
become eligible for resale pursuant to Rule 144(k) under the Act.

         6. No Impairment. The Company will not, by amendment of its charter or
through reorganization, consolidation, merger, dissolution, sale of assets or
any other voluntary action, avoid or seek to avoid the observance or performance
of any of the terms of this Warrant.

         7. Reservation of Stock. The Company will at all times reserve and keep
available, solely for issuance and delivery upon the exercise of this Warrant,
such number of Warrant Shares and other stock, securities and property, as from
time to time shall be issuable upon the exercise of this Warrant.

         8. Replacement of Warrants. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and (in the case of loss, theft or destruction) upon delivery of an
indemnity agreement (with, in the case of any Restricted Holder other than an
institutional investor, surety if reasonably required) in an amount reasonably
satisfactory to the Company, or (in the case of mutilation) upon surrender and
cancellation of this Warrant, the Company will issue, at its expense, in lieu
thereof, a new Warrant of like tenor.

         9. Mailing of Notices, etc. All notices and other communications from
the Company to the Registered Holder of this Warrant shall be mailed by
first-class certified or registered mail, postage prepaid, to the address
furnished to the Company in writing by the last Registered Holder of this
Warrant who shall have furnished an address to the Company in writing. All
notices and other communications from the Registered Holder of this Warrant or
in connection herewith to the Company shall be mailed by first-class certified
or registered mail, postage prepaid, to the Company at its principal office at
One IDEXX Drive, Westbrook, Maine 04092.

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         10.      No Rights as Stockholder.

                  (a) Until the exercise of this Warrant, the Registered Holder
of this Warrant shall not have or exercise any rights by virtue hereof as a
stockholder of the Company. Notwithstanding the foregoing, in the event (i) the
Company effects a split of the Common Stock by means of a stock dividend and the
exercise price of and the number of shares subject to this Warrant are adjusted
as of the date of the distribution of the dividend (rather than as of the record
date for such dividend), and (ii) the Registered Holder exercises this Warrant
between the record date and the distribution date for such stock dividend, the
Registered Holder shall be entitled to receive, on the distribution date, the
stock dividend with respect to the shares of Common Stock acquired upon such
exercise, notwithstanding the fact that such shares were not outstanding as of
the close of business on the record date for such stock dividend.

                  (b) If the Company pays any dividend upon the Common Stock
(whether payable in cash, securities or other property), other than a regular
cash dividend paid out of earnings or earned surplus (determined in accordance
with generally accepted accounting principles) or a stock dividend payable in
shares of Common Stock, then the Company will pay or distribute to the
Registered Holder of this Warrant, upon the exercise hereof, in addition to the
Warrant Shares purchased upon such exercise, such dividend which would have been
paid to such Registered Holder if he or she had been the owner of record of such
Warrant Shares immediately prior to the record date for such dividend or, if no
record is fixed, the date as of which the record holders of Common Stock
entitled to such dividend are to be determined.

         11. Cancellation of Warrant. The Registered Holder acknowledges and
agrees that this Warrant may be cancelled with respect to a portion of the
Warrant Shares in satisfaction of claims for which the Company is entitled to
indemnification in accordance with the terms of Article VI of the Stock Purchase
Agreement, as follows. If the Company has in good faith delivered a Claim Notice
or Expected Claim Notice (each as defined in the Stock Purchase Agreement)
within six months after the date of this Warrant claiming damages from the
Registered Holder, and such claim has not been paid by the Registered Holder or
otherwise resolved, then (subject to the limitations set forth in Article VI of
the Stock Purchase Agreement) the Company shall be entitled to delay the
exercise of such portion of this Warrant as has a value (determined pursuant to
Section 6.5 of the Stock Purchase Agreement) equal to the Claimed Amount (as
defined in the Stock Purchase Agreement) (or any lesser amount then claimed),
less any portion thereof as has actually been paid by the Registered Holder
pursuant to Article VI of the Stock Purchase Agreement with respect to such
claim. Upon the resolution of any indemnity claim that was the subject of an
exercise 

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delay under this Section 11, (i) the Company shall be entitled to cancel such
portion of this Warrant (subject to the limitation on the number of Warrant
Shares which may be cancelled set forth in Section 6.5(a) of the Stock Purchase
Agreement) as has a value (determined pursuant to Section 6.5 of the Stock
Purchase Agreement) equal to the amount of Damages (if any) the Company is
entitled to receive pursuant to the resolution of such indemnity claim (which
shall release the Registered Holder of its obligation to pay such amount to the
Company under Article VI of the Stock Purchase Agreement) and (ii) the right to
exercise the balance of such Warrant (to the extent then vested) shall be
immediately reinstated.

         12. Change or Waiver. This Warrant is one of a series of Warrants
issued by the Company, all dated the date hereof and substantially similar in
form, except as to the number of shares of Common Stock subject thereto
(collectively, the "Company Warrants"). Any term of this Warrant may be amended
or waived upon the written consent of the Company and the holders of Company
Warrants representing at least 70% of the number of shares of Common Stock then
subject to outstanding Company Warrants; provided that any such amendment or
waiver must apply to all Company Warrants then outstanding; and provided further
that the number of Warrant Shares subject to this Warrant and the Purchase Price
of this Warrant may not be amended, and the right to exercise this Warrant may
not be waived, without the written consent of the holder of this Warrant.

         13. Headings. The headings in this Warrant are for purposes of
reference only and shall not limit or otherwise affect the meaning of any
provision of this Warrant.

         14. Governing Law. This Warrant will be governed by and construed in
accordance with the laws of the State of Delaware.



                                      IDEXX LABORATORIES, INC.



                                      By:________________________________

                                      Title:_____________________________

ATTEST:



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                                                                       EXHIBIT I


                                  PURCHASE FORM


To: IDEXX LABORATORIES, INC.                         Dated:______________


         The undersigned, pursuant to the provisions set forth in the attached
Warrant (No. ___), hereby irrevocably elects to purchase _____ shares of the
Common Stock covered by such Warrant. The undersigned herewith makes payment of
$____________, representing the full purchase price for such shares at the price
per share provided for in such Warrant. Such payment takes the form of (check
applicable box or boxes):

                  _        $_________ in lawful money of the United States,
                           and/or

                  _        the cancellation of such portion of the attached
                           Warrant as is exercisable for a total of ______
                           Warrant Shares (using a Fair Market Value of $_______
                           per share for purposes of this calculation).


                                        Signature:__________________________

                                        Address:____________________________

                                                ____________________________



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