FIRST AMENDMENT TO CREDIT AGREEMENT


                    This First Amendment to Credit Agreement (this
          "Amendment") effective as of the 31st day of December, 1997,
          among INTERNATIONAL MUREX TECHNOLOGIES CORPORATION, MUREX
          DIAGNOSTICS INTERNATIONAL, INC., MUREX DIAGNOSTICS CORPORATION,
          IMTC HOLDINGS (UK) LIMITED, MUREX DIAGNOSTICS, INC. and MUREX
          BIOTECH LIMITED, as Borrowers (collectively, the "Borrowers" and
          each, a "Borrower"), BANK OF AMERICA NATIONAL TRUST AND SAVINGS
          ASSOCIATION (as successor by merger to Bank of America Illinois),
          and BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION,
          ACTING THROUGH ITS LONDON BRANCH, as Issuing Banks (collectively,
          the "Issuing Banks" and each, an "Issuing Bank"), BANK OF
          AMERICA, F.S.B., as Agent (the "Agent") and the financial
          institutions listed on the signature pages hereof as Lenders (the
          "Lenders"),

                                 W I T N E S S E T H:

                    WHEREAS, the Borrowers, the Lenders, the Issuing Bank
          and the Agent are parties to that certain Credit Agreement dated
          as of November 12, 1996 (as amended, restated, supplemented or
          otherwise modified from time to time, the "Credit Agreement");
          and

                    WHEREAS, the Borrowers have requested that certain
          terms of the Credit Agreement be amended, and the Agent, the
          Issuing Bank and the Lenders have agreed to the requested
          amendments on the terms and conditions set forth herein; and

                    NOW THEREFORE, in consideration of the foregoing
          premises and other good and valuable consideration paid by each
          party to the other, the receipt and sufficiency of which are
          hereby acknowledged, the parties hereby agree as follows:

               1.   Amendment to Article I.  Article I of the Credit
                    ----------------------
          Agreement, Definitions, is hereby amended by deleting the
                     -----------
          definitions of "BAI", "Borrower Representative", and "Borrowers"
                          ---    -----------------------        ---------
          set forth therein in their entirety and substituting the
          following, respectively, in their place:

                    ""BAI" means Bank of America National Trust and Savings
                      ---
               Association, as successor by merger to Bank of America
               Illinois.

                    "Borrower Representative" means International Murex
                     -----------------------
               Technologies Corporation, a corporation organized under the
               laws of the Province of British Columbia, or any other
               Borrower selected by the Borrowers in accordance with
               Section 2.20.
               ------------

                    "Borrowers" means International Murex Technologies
                     ---------
               Corporation, a corporation organized under the laws of the
               Province of British Columbia, Murex Diagnostics
               International, Inc., a corporation organized under the laws
               of Barbados, Murex Diagnostics Corporation, a corporation
               organized under the laws of Barbados, IMTC Holdings (UK)
               Limited, a corporation organized under the laws of England,
               Murex Diagnostics, Inc., a corporation organized under the
               laws of the State of Delaware (individually and as the
               successor by merger to IMTC Holdings, Inc.) and Murex
               Biotech Limited, a corporation organized under the laws of
               England, and "Borrower" means any of the foregoing."
                             --------

               2.   Amendment to Article VI.  Article VI of the Credit
                    -----------------------
          Agreement, Representations and Warranties, is hereby amended by
                     ------------------------------
          adding the following Section 6.27 to the end thereof:

                    "6.27  Year 2000 Compliance.  Each Borrower has
                           --------------------
               conducted a comprehensive review and assessment of its
               computer applications with respect to the "year 2000
               problem" (that is, the risk that computer applications may
               not be able to properly perform date-sensitive functions
               after December 31, 1999) and, based on that review, such
               Borrower does not believe the year 2000 problem will result
               in a material adverse change in such Borrower's business
               condition (financial or otherwise), operations, properties
               or prospects, or ability to repay the Obligations."

               3.   Amendment to Section 8.9.  Section 8.9 of the Credit
                    ------------------------
          Agreement, Contingent Obligations, is hereby deleted in its
                     ----------------------
          entirety and replaced with the following:

                    "8.9  Contingent Obligations.  IMTC shall not, and
                          ----------------------
               shall not suffer or permit any Material Subsidiary to,
               create, incur, assume or suffer to exist any Contingent
               Obligations except:

                         (a)  endorsements for collection or deposit in the
                    ordinary course of business;

                         (b)  Contingent Obligations of IMTC and its
                    Material Subsidiaries existing as of the Agreement Date
                    and listed in Schedule 8.9;
                                  ------------

                         (c)  Guaranty Obligations entered into by (i) IMTC
                    not exceeding $1,450,000 in the aggregate at any time
                    outstanding with respect to obligations of Murex
                    Biotech S.A. (Pty) Limited in connection with the
                    construction of a manufacturing facility in South
                    Africa, and (ii) IMTC or any Material Subsidiary after
                    the Agreement Date with respect to any other
                    obligations of an Affiliate of IMTC and not exceeding
                    $1,000,000 in the aggregate at any time outstanding."

               4.   Amendment to Section 8.18.  Section 8.18 of the Credit
                    -------------------------
          Agreement, Capital Expenditures, is hereby deleted in its
                     --------------------
          entirety and replaced with the following:

                    "8.18  Capital Expenditures.  IMTC and its Subsidiaries
                           --------------------
               shall not make or incur during (a) the fiscal year ending on
               December 31, 1997, in the aggregate any Capital Expenditures
               in excess of $10,500,000 and (b) the fiscal year ending on
               December 31, 1998, and during each fiscal year thereafter,
               in the aggregate any Capital Expenditures in excess of
               $7,000,000."

               5.   No Other Amendment.  Except for the amendments
                    ------------------
          expressly set forth above, the text of the Credit Agreement and
          all other Loan Documents shall remain unchanged and in full force
          and effect.  Each Borrower acknowledges and expressly agrees that
          the Lenders reserve the right to, and do in fact, require strict
          compliance with all terms and provisions of the Credit Agreement
          and the other Loan Documents.

               6.   Representations and Warranties.  Each Borrower hereby
                    ------------------------------
          represents and warrants in favor of the Agent, the Issuing Banks,
          and each Lender, as follows:

                    (a)  such Borrower has the corporate power and
               authority (i) to enter into this Amendment, and (ii) to do
               all acts and things as are required or contemplated
               hereunder to be done, observed and performed by it;

                    (b)  this Amendment has been duly authorized, validly
               executed and delivered by one or more authorized signatories
               of such Borrower, and constitutes the legal, valid and
               binding obligation of the Borrower, enforceable against such
               Borrower in accordance with its terms;

                    (c)  the execution and delivery of this Amendment and
               performance by such Borrower under the Credit Agreement, as
               amended hereby, do not and will not require the consent or
               approval of any regulatory authority or governmental
               authority or agency having jurisdiction over such Borrower
               which has not already been obtained, nor contravene or
               conflict with the charter documents of such Borrower, or the
               provisions of any statute, judgment, order, indenture,
               instrument, agreement or undertaking, to which such Borrower
               is a party or by which any of its properties are or may
               become bound; and

                    (d)  as of the date hereof, and after giving effect to
               this Amendment (i) no Default or Event of Default exists
               under the Credit Agreement or is caused by this Amendment,
               and (ii) each presentation and warranty set forth in Article
               VI of the Credit Agreement is true and correct in all
               material respects, except (x) to the extent previously
               fulfilled in accordance with the terms of the Credit
               Agreement, as amended hereby, or (y) to the extent
               specifically relating to the Agreement Date.

               7.   Loan Document.  This Amendment shall be deemed to be a
                    -------------
          Loan Document for all purposes.

               8.   Expenses.  The Borrowers agree to pay all reasonable
                    --------
          expenses of the Agent incurred in connection with this Amendment,
          including, without limitation, all fees and expenses of counsel
          to the Agent.

               9.   Counterparts.  This Amendment may be executed in
                    ------------
          multiple counterparts, each of which shall be deemed to be an
          original and all of which, taken together, shall constitute one
          and the same agreement.  Delivery of an executed counterpart of
          this Amendment by facsimile transmission shall be as effective as
          delivery of a manually executed counterpart hereof.

               10.  Governing Law.  This Amendment shall be deemed to be
                    -------------
          made pursuant to the laws of the State of Georgia with respect to
          agreements made and to be performed wholly in the State of
          Georgia, and shall be construed, interpreted, performed and
          enforced in accordance therewith.

               11.  Definitions.  All capitalized terms not otherwise
                    -----------
          defined herein shall have the meanings set forth in the Credit
          Agreement.

               12.  Effectiveness.  This Amendment shall be effective as of
                    -------------
          the date first set forth above upon the Agent's receipt of a
          counterpart hereof duly executed by the Borrowers, the Issuing
          Banks and the Lenders.


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          <PAGE>


                    IN WITNESS WHEREOF, the parties hereto have executed
          this Amendment or caused it to be executed by their duly
          authorized officers, effective as of the day and year first
          written above.


          BORROWERS:                    INTERNATIONAL MUREX TECHNOLOGIES
                                        CORPORATION

                                        By:  /s/ Steven C. Ramsey
                                           ----------------------------
                                        Title:     CFO
                                              -------------------------


                                        MUREX DIAGNOSTICS INTERNATIONAL,
                                        INC.

                                        By:   /s/ Steven C. Ramsey
                                           ---------------------------
                                        Title:     Director
                                              ------------------------


                                        MUREX DIAGNOSTICS CORPORATION

                                        By:    /s/ Steven C. Ramsey
                                           ---------------------------
                                        Title:   Director
                                              ------------------------


                                        IMTC HOLDINGS (UK) LIMITED

                                        By:   /s/ Steven C. Ramsey
                                           ---------------------------
                                        Title:   Director
                                              ------------------------


                                        MUREX DIAGNOSTICS, INC.

                                        By:   /s/ Steven C. Ramsey
                                           ----------------------------
                                        Title:    VP Finance
                                              -------------------------


                                        MUREX BIOTECH LIMITED

                                        By:   /s/ Steven C. Ramsey
                                           -----------------------------
                                        Title:    Director
                                              --------------------------


          AGENT:                        BANK OF AMERICA, FSB

                                        By:   /s/ John Yankavskas
                                           -----------------------------
                                        Title:    V.P.
                                              --------------------------


          LENDERS:                      BANK OF AMERICA, FSB

                                        By:  /s/ John Yankavskas
                                           ------------------------------
                                        Title:   V.P.
                                              ---------------------------


                                        BANK OF AMERICA NATIONAL TRUST AND
                                        SAVINGS ASSOCIATION, acting through
                                        its London Branch

                                        By:   /s/ Keith Thomas
                                           ------------------------------
                                        Title:    Vice President
                                              ---------------------------


          ISSUING BANKS:                BANK OF AMERICA NATIONAL TRUST AND
                                        SAVINGS ASSOCIATION

                                        By:   /s/ Ginger Trimble
                                           ------------------------------
                                        Title:    Vice President
                                              ---------------------------


                                        BANK OF AMERICA NATIONAL TRUST AND
                                        SAVINGS ASSOCIATION, acting through
                                        its London Branch

                                        By:   /s/ Keith Thomas
                                           ------------------------------
                                        Title:    Vice President
                                              ---------------------------