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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   Form 8-A/A
                                 AMENDMENT NO. 1

                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                            IDEXX LABORATORIES, INC.
             ------------------------------------------------------
             (Exact name of registrant as specified in its charter)


             Delaware                                    01-0393723
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     (State of incorporation                         (IRS Employer
         or organization)                            Identification No.)


     One Idexx Drive, Westbrook, ME                      04092
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(Address of principal executive offices)               (Zip Code)


If this Form relates to the registration of a class of securities pursuant to
Section 12(b) of the Exchange Act and is effective pursuant to General
Instruction A.(c), please check the following box. [ ]

If this Form relates to the registration of a class of securities pursuant to
Section 12(g) of the Exchange Act and is effective pursuant to General
Instruction A.(d), please check the following box. [ ]

Securities Act registration statement number to which this form
relates:
          -----------------------
              (If applicable)

Securities to be registered pursuant to Section 12(b) of the Act: None

Securities to be registered pursuant to Section 12(g) of the Act:


                         Preferred Stock Purchase Rights
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                    (Title of each class to be so registered)


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Explanatory Note:

     This Amendment No. 1 to Registration Statement on Form 8-A/A amends and
restates the Registration Statement on Form 8-A dated December 24, 1996 (the
"Form 8-A"), filed by IDEXX Laboratories, Inc. (the "Company") with respect to
the Preferred Stock Purchase Rights (the "Rights") issued pursuant to the Rights
Agreement dated as of December 17, 1996 between the Company and BankBoston, N.A.
(formerly known as The First National Bank of Boston), as Rights Agent (the
"Rights Agent"). On July 22, 1999, the Company and the Rights Agent entered into
Amendment No. 1 to Rights Agreement ("Amendment No. 1"), which is included as
Exhibit 2 hereto and is incorporated herein by reference. Amendment No. 1
amended the Rights Agreement to: (i) eliminate provisions related to "Continuing
Directors," (ii) eliminate provisions related to "Permitted Offers," and (iii)
make certain other revisions. The Rights Agreement, as amended through the date
hereof, is referred to herein as the "Rights Agreement."

Item 1.   Description of Registrant's Securities to be Registered.

     On December 17, 1996, the Board of Directors of the Company, declared a
dividend of one preferred stock purchase right (a "Right") for each outstanding
share of the Company's Common Stock to stockholders of record at the close of
business on December 30, 1996 (the "Record Date"). Each Right entitles the
registered holder to purchase from the Company a unit consisting of one
one-thousandth of a share (a "Unit") of Series A Junior Participating Preferred
Stock, $1.00 par value per share (the "Preferred Stock"), at a purchase price of
$200.00 in cash per Unit (the "Purchase Price"), subject to adjustment. The
description and terms of the Rights are set forth in the Rights Agreement dated
as of December 17, 1996 between the Company and BankBoston, N.A. (formerly known
as The First National Bank of Boston), as amended on July 22, 1999.

     Initially, the Rights will be attached to all Common Stock certificates
representing shares then outstanding, and no separate Rights Certificates will
be distributed. The Rights will separate from the Common Stock and a
Distribution Date will occur upon the earlier of (i) ten business days (or such
later date as may be determined by the Board of Directors of the Company)
following a public announcement that a person or group of affiliated or
associated persons (an "Acquiring Person") has acquired, or obtained the right
to acquire, beneficial ownership of 20% or more of the outstanding shares of
Common Stock (the "Stock Acquisition Date"), or (ii) ten business days (or such
later date as may be determined by the Board of Directors of the Company)
following the commencement of a tender offer or exchange offer that


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would result in a person or group beneficially owning 30% or more of such
outstanding shares of Common Stock. Until the Distribution Date (or earlier
redemption or expiration of the rights), (i) the Rights will be evidenced by the
Common Stock certificates and will be transferred with and only with such Common
Stock certificates, (ii) new Common Stock certificates issued after the Record
Date will contain a notation incorporating the Rights Agreement by reference and
(iii) the surrender for transfer of any certificates for Common Stock
outstanding, even without such notation, will also constitute the transfer of
the Rights associated with the Common Stock represented by such certificate.

     The Rights are not exercisable until the Distribution Date and will expire
upon the earliest of the close of business on December 30, 2006 (the "Final
Expiration Date") or the redemption or exchange of the Rights as described
below.

     As soon as practicable after the Distribution Date, separate certificates
evidencing the Rights ("Rights Certificates") will be mailed to holders of
record of the Common Stock as of the close of business on the Distribution Date
and, thereafter, such separate Rights Certificates alone will represent the
Rights. Except as otherwise determined by the Board of Directors and except in
connection with shares of Common Stock issued upon the exercise of employee
stock options, issuances under other employee stock benefit plans or the
conversion of convertible securities issued hereafter, only shares of Common
Stock issued prior to the Distribution Date will be issued with Rights.

     In the event that any Person becomes an Acquiring Person then, promptly
following the first occurrence of such event, proper provision shall be made so
that each holder of a Right (except as provided below and in Section 7(e) of the
Rights Agreement) shall thereafter have the right to receive, upon exercise
thereof at the then current Purchase Price, in lieu of a number of one
one-thousandths of a share of Preferred Stock, such number of shares of Common
Stock of the Company that equals the result obtained by (x) multiplying the then
current Purchase Price by the then number of one one-thousandths of a share of
Preferred Stock for which a Right is then exercisable, and (y) dividing that
product by 50% of the current market price per share of Common Stock on the date
of such first occurrence. Notwithstanding any of the foregoing, following the
occurrence of the event set forth in this paragraph, all Rights that are, or
(under certain circumstances specified in the Rights Agreement) were,
beneficially owned by any Acquiring Person will be null and void. The event
summarized in this paragraph is referred to as "Section 11(a)(ii) Event."

     In the event that, at any time after any Person becomes an Acquiring
Person, (i) the Company is acquired in a merger or other business combination
transaction in which the Company is not the surviving corporation or its Common
Stock is changed or exchanged, or (ii) 50% or more of the Company's assets or
earning power is sold or


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transferred, each holder of a Right (except Rights which previously have been
voided as set forth above) shall thereafter have the right to receive, upon
exercise, that number of shares of Common Stock of the acquiring company which
equals the exercise price of the Right divided by one-half of the current market
price of such Common Stock at the date of the occurrence of the event. The
events summarized in this paragraph are referred to as "Section 13 Events."
Section 11(a)(ii) Events and Section 13 Events are collectively referred to as
"Triggering Events."

     At any time after the occurrence of a Section 11(a)(ii) Event, subject to
certain conditions, the Board of Directors of the Company may exchange the
Rights (other than Rights owned by such Acquiring Person which have become
void), in whole or in part, at an exchange ratio of one share of Common Stock,
or one one-thousandth of a share of Preferred Stock (or of a share of a class or
series of the Company's preferred stock having equivalent rights, preferences
and privileges), per Right (subject to adjustment).

     The Purchase Price payable, and the number of Units of Preferred Stock or
other securities or property issuable, upon exercise of the Rights are subject
to adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Stock, (ii) if holders of the Preferred Stock are granted certain rights or
warrants to subscribe for Preferred Stock or convertible securities at less than
the then-current market price of the Preferred Stock, or (iii) upon the
distribution to holders of the Preferred Stock of evidences of indebtedness or
assets (excluding regular periodic cash dividends paid out of earnings or
retained earnings) or of subscription rights or warrants (other than those
referred to above).

     The number of Rights associated with each share of Common Stock is also
subject to adjustment in the event of a stock split of the Common Stock or a
stock dividend on the Common Stock payable in Common Stock or subdivisions,
consolidations or combinations of the Common Stock occurring, in any such case,
prior to the Distribution Date.

     Preferred Stock purchasable upon exercise of the Rights will not be
redeemable. Each share of Preferred Stock will be entitled to a minimum
preferential quarterly dividend payment of $10 per share and will be entitled to
an aggregate dividend of 1000 times the dividend declared per share of Common
Stock. In the event of liquidation, the holders of the Preferred Stock will be
entitled to a minimum preferential liquidation payment of $1000 per share and
will be entitled to an aggregate payment of 1000 times the payment made per
share of Common Stock. Each share of Preferred Stock will have 1000 votes,
voting together with the Common Stock. In the event of any merger, consolidation
or other transaction in which Common Stock is exchanged, each share of Preferred
Stock will be entitled to receive 1000 times the amount received per share of
Common Stock. These rights are protected by customary antidilution provisions.

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     Because of the nature of the Preferred Stock's dividend, liquidation and
voting rights, the value of one one-thousandth of a share of Preferred Stock
purchasable upon exercise of each Right should approximate the value of one
share of Common Stock.

     With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments amount to at least 1% of the Purchase
Price. No fractional Units will be issued and, in lieu thereof, an adjustment in
cash will be made based on the market price of the Preferred Stock on the last
trading date prior to the date of exercise.

     At any time prior to the earlier of (i) ten business days (or such later
date as may be determined by the Board of Directors of the Company) following
the Stock Acquisition Date or (ii) the Final Expiration Date, the Company may
redeem the Rights in whole, but not in part, at a price of $.01 per Right (the
"Redemption Price"), payable in cash. Immediately upon the action of the Board
of Directors ordering redemption of the Rights, the Rights will terminate and
the only right of the holders of Rights will be to receive the Redemption Price.

     Until a Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of the Company, including, without limitation, the right
to vote or to receive dividends. While the distribution of the Rights will not
be taxable to stockholders or to the Company, stockholders may, depending upon
the circumstances, recognize taxable income in the event that the Rights become
exercisable for Common Stock (or other consideration) of the Company or for
Common Stock of the acquiring company as set forth above.

     Subject to certain exceptions, any of the provisions of the Rights
Agreement may be amended by the Board of Directors of the Company prior to such
time as the Rights are no longer redeemable.

     A copy of the Rights Agreement dated as of December 17, 1996 between the
Company and the Rights Agent, which includes as Exhibit A, the Form of
Certificate of Designations and as Exhibit B, the Form of Rights Certificate, is
filed as Exhibit 1 to the Form 8-A and is incorporated herein by reference.
Amendment No. 1 is filed as Exhibit 2 hereto and is incorporated herein by
reference. The foregoing description of the Rights Agreement and the Rights does
not purport to be complete and is qualified in its entirety by reference to such
Exhibits.

Item 2.   Exhibits.

1              Rights Agreement dated as of December 17, 1996 between the
               Company and BankBoston, N.A. (formerly known as The First
               National Bank of

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               Boston) is incorporated herein by reference to Exhibit 1 to
               the Company's Registration Statement on Form 8-A (File No.
               000-19271)

2              Amendment No. 1 to Rights Agreement dated as of July 22, 1999
               between the Company and BankBoston, N.A. (formerly known as The
               First National Bank of Boston)

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                                    SIGNATURE


     Pursuant to the requirements of Section 12 of the Securities Exchange Act
of 1934, the Registrant has duly caused this Amendment No. 1 to Registration
Statement to be signed on its behalf by the undersigned, thereto duly
authorized.


                                            IDEXX LABORATORIES, INC.



Date: July 30, 1999                    By: /s/ Ralph K. Carlton
                                           __________________________
                                           Ralph K. Carlton
                                           Senior Vice President
                                           Finance and Administration



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                                  EXHIBIT INDEX


Exhibit No.                          Description

1         Rights Agreement dated as of December 17, 1996 between the Company and
          BankBoston, N.A. (formerly known as The First National Bank of Boston)
          is incorporated herein by reference to Exhibit 1 to the Company's
          Registration Statement on Form 8-A (File No. 000-19271)

2         Amendment No. 1 to Rights Agreement dated as of July 22, 1999 between
          the Company and BankBoston, N.A. (formerly known as The First National
          Bank of Boston)


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