EXHIBIT 10.18


                    COOPERATION AND COLLABORATION AGREEMENT


    THIS COOPERATION AND COLLABORATION AGREEMENT is made and entered into by and
between Dade Behring Holdings, Inc., a Delaware corporation, and Hoechst AG, a
German corporation.

    WHEREAS, pursuant to the Combination Agreement (as defined below), Hoechst
AG has transferred its diagnostics business to Diagnostic Holdings, Inc. in
exchange for an equity interest in Diagnostic Holdings, Inc.;

    WHEREAS, following consummation of such combination, Diagnostic Holdings,
Inc. has changed its name to Dade Behring Holdings, Inc.;

    WHEREAS, in connection with the combination of Hoechst AG's diagnostics
business with and into the business of Dade Behring Holdings, Inc., Hoechst AG
and Dade Behring Holdings, Inc. have agreed to set forth a set of basic
principles to govern their future discussions concerning strategies and
potential projects for cooperation and collaboration in the areas more fully
described below; and

    WHEREAS, Dade Behring Holdings, Inc. and Hoechst AG acknowledge that any
such close cooperation and collaboration is intended to ensure a smooth
transition period for the combination of the two business units and to create
synergy effects for the mutual benefit of the parties, which constitutes an
essential element in particular for Hoechst AG to enter into said combination.

     NOW, THEREFORE, the parties hereby agree as follows:





                             COOPERATION AGREEMENT

 
                                       2

1   DEFINITIONS

The following terms when used herein with initial capital letters shall have the
respective meanings set forth below.

    1.1  Areas of Collaboration.  The term "Areas of Collaboration" shall mean
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         access to existing technology, research and development of new
         technology, manufacturing and marketing of products, all with
         applicability to both the Life Science Field and the Diagnostic Field
         as further described in clause 2.1.

    1.2  Combination Agreement.  The term "Combination Agreement" shall refer to
         ---------------------                                                  
         the Agreement and Plan of Combination dated June 24, 1997 between
         Hoechst and DBI.

    1.3  Confidential Information. The term "Confidential Information" shall
         ------------------------
         mean any and all tangible and intangible information of either party,
         whether oral or in writing or in any other medium, relating to the
         management, operations, finances, products and technology of the
         disclosing party, including, without limitation, any and all trade
         secrets, inventions, know-how, designs, formulations, ingredients,
         samples, processes, machines, processing and control information,
         product performance dates, manuals, supplier lists, consumer lists,
         purchase and sales records, marketing information and computer programs
         in each case whether developed by the disclosing party or furnished to
         the disclosing party by other parties.

    1.4  Cooperation Agreement.  The term "Cooperation Agreement" shall refer to
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         this agreement.

    1.5  Diagnostics Field. The term "Diagnostics Field" shall mean the
         -----------------
         research, development, manufacture, marketing, sale, distribution and
         service of human in vitro diagnostic equipment, reagents, consumable
         supplies and services.


                             COOPERATION AGREEMENT

 
                                       3

    1.6  DBI.  The term "DBI" shall mean Dade Behring Holdings, Inc. (formerly
         ---                                                                  
         known as Diagnostic Holdings, Inc.) and any subsidiaries of DBI in
         which it holds direct or indirect beneficial ownership of more than 50%
         of the voting stock.

    1.7  Effective Date.  The term "Effective Date" shall mean the date of the
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         closing of the transactions contemplated by the Combination Agreement.

    1.8  Hoechst.  The term "Hoechst" shall mean Hoechst AG and any subsidiaries
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         of Hoechst in which it holds direct or indirect beneficial ownership of
         more than 50% of the voting stock.

    1.9  Life Sciences Field.  The term "Life Sciences Field" shall mean the
         -------------------                                                
         research, development, manufacture, marketing, sale, distribution and
         service of pharmaceuticals, agricultural products and veterinary
         medical products.

    1.10 Specific Collaboration Agreement.  The term "Specific Collaboration
         --------------------------------                                   
         Agreement" shall mean an agreement setting forth terms and conditions
         agreed to by the parties under which they shall pursue projects in the
         Areas of Collaboration that have been approved by the Steering
         Committee.

    1.11 Steering Committee.  The term "Steering Committee" shall mean a
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         committee composed of an equal number of representatives appointed by
         each of the parties that shall meet with a view to implement projects
         in the Areas of Collaboration.

2   SCOPE OF COLLABORATION

    2.1  In General.  The parties regard each other as principal collaborators
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         such as that DBI shall be Hoechst's principal collaborator in the
         Diagnostic Field and Hoechst shall be DBI's principal collaborator in

                             COOPERATION AGREEMENT

 
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         the Life Sciences Field. The parties shall cooperate in good faith to
         identify and discuss potential projects within the Areas of
         Collaboration whereby both parties may benefit from a collaborative
         effort.

    2.2  Areas of Consideration.  The parties are in agreement that the areas to
         ----------------------                                                 
         be considered for collaboration include:

         2.2.1  the development of new technology including but not limited to
                areas of: (i) specific diseases, such as cardiovascular
                diseases, oncology, osteoporosis, infections, rheumatics,
                allergies and Alzheimer's disease; (ii) bioinformatics (i.e.,
                                                                        ----
                information received through genome sequencing); and (iii)
                clinical trials (e.g., the development of tests for drug
                                 ----
                monitoring and in the field of pharmacokinetics; acquisition
                of clinical utility information on DBI products with DBI bearing
                any associated incremental costs);

         2.2.2  marketing collaboration including, but not limited to, the areas
                of: (i) disease management, e.g., in the areas of cardiovascular
                                            ----
                diseases, rheumatoid arthritis and diseases of CNS; (ii) the
                production of brochures, information and advertising materials;
                (iii) the sponsoring of congresses and opinion leaders; (iv) the
                coordination of visits of clinics and presentation to the
                public; and

         2.2.3  collaboration in the field of "managed care".

    2.3  Existing Collaborations.  To the extent there is not a formal
         -----------------------                                      
         collaboration agreement already in place, any collaboration efforts
         begun prior to the Effective Date between Hoechst and the diagnostics
         business of Hoechst (which has now been transferred to DBI pursuant to
         the Combination Agreement) shall be governed by the terms of Specific
         Collaboration Agreements which are to be negotiated in good 


                             COOPERATION AGREEMENT

 
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          faith between Hoechst and DBI as soon as practical after the Effective
          Date.

          Nothing in this Collaboration Agreement shall be construed such as
          that it will interfere with existing agreements or negotiations with
          any third party.

    2.4   New Collaborations.  This Cooperation Agreement shall not in any way
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          prohibit either party from collaborating or cooperating with any third
          party, or from undertaking projects on its own, in any area of
          endeavor, including but not limited to the Areas of Collaboration;
          provided, however, that each party shall treat the other as its
          --------  -------
          principal collaborator as set forth in clause 2.1 and consistent
          therewith shall first offer the other party the opportunity to enter
          into any collaboration contemplated by such party in the Areas of
          Collaboration prior to entering into a comparable arrangement with any
          third party unless such party has a good faith business justification
                      ------
          for choosing not to collaborate with the other party on a particular
          project. In any event, the parties will use good faith efforts to
          inform each other prior to entering into detailed discussions with
          third parties about the intent to collaborate or cooperate within the
          Areas of Collaboration it being the intention that both parties should
          be free of outside constraints when evaluating the benefit of entering
          into a joint collaboration or cooperation.

          Notwithstanding anything in this Cooperation Agreement to the
          contrary, it is understood and agreed between the parties that nothing
          in this Cooperation Agreement shall prevent (i) DBI from entering into
          collaborations or other arrangements with third party pharmaceutical
          companies in connection with antimicrobial susceptibility testing
          associated with antimicrobial therapy or (ii) Hoechst from entering
          into collaborations or other arrangements with third party companies
          in connection with decentralized near-patient point of care testing
          and direct pharmaceutical therapy, provided that such third party
          companies 


                             COOPERATION AGREEMENT

 
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          are not in competition with the business of DBI as it exists as of the
          date hereof.

    2.5   Steering Committee.
          ------------------ 

          2.5.1  The parties shall form a Steering Committee that will meet on a
                 regular basis during the term of this Cooperation Agreement to
                 present ideas, exchange information, identify potential
                 collaboration projects and ultimately decide about joint
                 projects subject to each party's formal approval. The Steering
                 Committee shall agree upon the timing and location of its
                 meetings. The Chairman of the Strategy Committee of DBI shall
                 serve as the Chairman of the Steering Committee. On the
                 Effective Date, the Chairman of the Steering Committee shall be
                 Uwe Bicker. The Steering Committee members shall be executives
                 of the respective parties that possess the technical knowledge
                 and skill applicable to the Areas of Collaboration.

          2.5.2  Should the Steering Committee unanimously agree to pursue a
                 project within the Areas of Collaboration, it shall appoint the
                 appropriate personnel to determine the specific structure,
                 terms, conditions and other relevant details for a Specific
                 Collaboration Agreement that shall govern such project. The
                 Steering Committee shall oversee and coordinate the
                 implementation of the projects. Any differences at the working
                 level shall be discussed by the Steering Committee with the
                 endeavor to amicably settle such difference.

    2.6   Procedures.  If at any time either DBI or Hoechst desires to pursue a
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          collaboration project within the Area of Collaboration, then the
          relevant company shall deliver a written notice to the Chairman of the
          Steering Committee describing such proposed project or activity in
          reasonable detail. The Chairman of the Steering Committee will
          distribute such proposal to the other members of the Steering
          Committee and to the 


                             COOPERATION AGREEMENT

 
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          addressed company. The parties will discuss any such proposals within
          the next Steering Committee meeting or thereafter, if reasonable, and
          decide whether to pursue such proposal.

    2.7   Specific Collaboration Agreements.  To the extent appropriate Specific
          ---------------------------------                                     
          Collaboration Agreements shall include terms that address the
          following:

          (a)  project objectives and overview;

          (b)  project approach and organization;

          (c)  responsibilities and contributions of each of the parties;

          (d)  scheduling, milestones and work plans;

          (e)  protection and maintenance of jointly-developed intellectual and
               industrial property rights;

          (f)  estimated fees and expenses;

          (g)  responsibility for and documentation of costs, fees and expenses;

          (h)  cross-licensing and sub-licensing arrangements;

          (i)  confidentiality provisions;

          (j)  termination rules (including survival after termination of this
               Cooperation Agreement);

          (k)  any terms different from those set forth in this Collaboration
               Agreement that shall govern that project; and

          (l)  any other relevant terms.

                             COOPERATION AGREEMENT

 
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    2.8   Jointly-Developed Inventions.  Hoechst shall grant to DBI in the
          ----------------------------                                    
          Diagnostics Field, and DBI shall grant to Hoechst in the Life Sciences
          Field, a license to practice inventions developed jointly by the
          parties pursuant to a collaboration. The terms and conditions of such
          licenses, as well as licenses of such jointly developed technology in
          areas outside the Diagnostics and Life Sciences Fields, including but
          not limited to royalty rates, territory and exclusivity, shall be
          negotiated in good faith between the parties and, if agreed to prior
          to the commencement of a collaboration, shall be set forth in the
          applicable Specific Collaboration Agreement. In recognition of the
          parties choosing each other as their principal collaborator, the terms
          of such licenses shall contain "most favored licensee" provisions such
          that in the event the licensing party subsequently grants a third
          party a license to the same technology on terms and conditions that,
          taken in their entirety, are more favorable than those granted to the
          other party hereto, the other party hereto shall receive the benefit
          of such more favorable terms, provided that such party also accepts
          all other terms and conditions included in the third party license
          agreement.

    2.9   Ownership of Inventions. Nothing herein shall be construed to restrict
          -----------------------
          either party's ownership of or ability to use and otherwise exploit
          inventions and intellectual property developed solely by that party.
          If such invention or intellectual property is developed pursuant to a
          Specific Collaboration Agreement, the exploitation of such invention
          or intellectual property is subject to the terms of such agreement.

    2.10  Intellectual Property.  Nothing in this Cooperation Agreement shall be
          ---------------------                                                 
          construed to grant or convey to either party any title or right to any
          intellectual or industrial property rights, including but not limited
          to any patents, copyrights, trade secrets or trademarks, of the other
          party.


                             COOPERATION AGREEMENT

 
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3   CONFIDENTIALITY

    3.1   In General. Each of the parties acknowledges that it will likely be in
          ----------
          both parties' interest to disclose or provide access to certain
          Confidential Information to the other party in order to realize any
          benefit from the collaborations contemplated by this Cooperation
          Agreement. The parties agree that any such disclosure or access shall
          be permitted only to the extent necessary to fulfill its obligation of
          cooperation pursuant to a Specific Collaboration Agreement or
          hereunder, and that such access shall be permitted only on the terms
          set forth in this Cooperation Agreement or, as applicable, the
          Specific Collaboration Agreement.

    3.2   Limited Transfer of Confidential Information. To the extent that
          --------------------------------------------
          either party elects to disclose certain Confidential Information to
          the other party, the receiving party agrees that:

          3.2.1  it will not use any Confidential Information for any purpose
                 other than in connection with a collaborative project
                 undertaken pursuant to the terms herein and in the Specific
                 Collaboration Agreement, as applicable;

          3.2.2  it will not disclose, utilize, exploit or distribute the
                 Confidential Information or the terms of this Cooperation
                 Agreement or any Specific Collaboration Agreement, or cause the
                 Confidential Information to be exploited or distributed to any
                 third party, except with the prior written consent of the
                 disclosing party;

          3.2.3  it shall take all reasonable steps to protect the Confidential
                 Information from disclosure and, in any event, employ means to
                 protect the Confidential Information that are at least as
                 stringent as those employed to protect its own Confidential
                 Information; and


                             COOPERATION AGREEMENT

 
                                       10

          3.2.4  it will not make or permit to be made, without the prior
                 written consent of the disclosing party, any copies or other
                 reproductions of the Confidential Information that the
                 disclosing party may supply to the receiving party hereunder.

    3.3   Exceptions.  The limitations imposed by this Section shall not apply
          ----------
          to:

          3.3.1  information which at the time of disclosure is already
                 possessed by the receiving party as demonstrated by written or
                 other tangible evidence;

          3.3.2  information that is or becomes part of the public domain
                 through no fault of the receiving party;

          3.3.3  information disclosed to the receiving party in good faith by a
                 third party who has an independent right to such information;

          3.3.4  information that is independently developed by an employee of
                 the receiving party who has not received or otherwise been
                 exposed to the information of the other party.

    3.4   Injunctive Relief.   Each party acknowledges and agrees that the
          -----------------                                               
          Confidential Information of the other party is valuable and
          confidential proprietary information of the other party, that the
          unauthorized disclosure of any part of the Confidential Information
          would cause the other party substantial and irreparable injury, and
          the other party will not have an adequate remedy at law in the event
          of such unauthorized disclosure. Therefore, each party acknowledges
          and agrees that the other party shall be entitled to obtain
          preliminary and permanent injunctive relief in any court of competent
          jurisdiction against acts of unauthorized disclosure of the
          Confidential Information, without the posting of bond or other
          security, in addition to whatever other remedies it may have at law or
          otherwise.


                             COOPERATION AGREEMENT

 
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    3.5   Return of Materials. To the extent that either party no longer
          -------------------
          requires Confidential Information it has received from the other
          party, or upon termination of this Cooperation Agreement for any
          reason, or upon the request of the disclosing party, each party shall
          promptly return to the disclosing party all documents and materials
          containing Confidential Information and shall either return or destroy
          all copies, extracts, summaries, analyses or reproductions containing
          any Confidential Information, as well as all documents, memoranda,
          notes and other writings prepared by the receiving party or its agents
          that are based in whole or in part on any Confidential Information.
          The receiving party shall provide the disclosing party with a written
          certification by an authorized officer that such destruction has taken
          place.

    3.6   No Warranties. Each of the parties acknowledges that neither party
          -------------
          makes any express or implied representation or warranty as to the
          accuracy, completeness, usefulness or reliability of the Confidential
          Information. Neither party nor any of its representatives shall have
          any liability to the other party, express or implied, relating to the
          use of its Confidential Information or for any errors therein or
          omissions therefrom.


4   TERM AND IMMEDIATE TERMINATION

    4.1   Term. This Cooperation Agreement shall be in effect from the Effective
          ----
          Date and shall continue for three (3) years. It shall automatically
          renew for another one-(1)-year period unless terminated by either
          party with a notice period of ninety (90) days before the start of any
          such one-(1)-year period.

    4.2   Immediate Termination.  This Cooperation Agreement shall, however,
          ---------------------                                             
          terminate immediately on the date on which Hoechst (and its
          Affiliates) own less than 75% of the Initial Hoechst Shares. The terms
          "Affiliate" and "Initial Hoechst Shares" shall have the meanings set
          forth in that 


                             COOPERATION AGREEMENT

 
                                       12

          certain Stockholders Agreement dated the date hereof by and between
          Hoechst and certain stockholders of Diagnostic Holdings, Inc. (now
          Dade Behring Holdings, Inc.).

    4.3   Termination for Breach.  Either party may terminate this Cooperation
          ----------------------                                              
          Agreement upon ninety (90) days' prior written notice, in the event of
          the other party's breach which is not cured within such ninety (90)
          day period.

5   MISCELLANEOUS

    5.1   Amendment and Waiver. This Cooperation Agreement may be amended, or
          any provision of this Cooperation Agreement may be waived, so long as
          any such amendment or waiver is set forth in a writing executed by
          each party hereto. No course of dealing between or among the parties
          shall be deemed effective to modify, amend or discharge any part of
          this Cooperation Agreement or any rights or obligations of any party
          under or by reason of this Cooperation Agreement.

    5.2   Notices. All notices, demands and other communications to be given or
          -------
          delivered under or by reason of the provisions of this Cooperation
          Agreement shall be in writing and shall be deemed to have been given
          when personally delivered, sent by telecopy (with receipt confirmed)
          or two days after sent by reputable overnight express courier (charges
          prepaid). Unless another address is specified in writing, notices,
          demands and communications to Hoechst and DBI shall be sent to the
          addresses indicated below:


                             COOPERATION AGREEMENT

 
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          Notices to Hoechst:
          ------------------ 

               Hoechst AG
               Bruningstrae 50
               D-65929 Frankfurt a.M.
               Germany
               Attn:  Horst Waesche, Member of the Management Board

          Notices to DBI:
          -------------- 

               Dade Behring Holdings, Inc.
               1717 Deerfield Road
               P.O. Box 778
               Deerfield, Illinois  60015
               U.S.A.
               Attn:  President
    
          with copy (which shall not constitute notice hereunder) to:
          ---------------------------------------------------------- 

               Bain Capital, Inc.
               Two Copley Place
               Boston, Massachusetts  02116
               U.S.A.
               Attn:  Stephen G. Pagliuca
                      John Connaughton

    5.3   Assignment. This Cooperation Agreement and all of the provisions
          ----------
          hereof are personal to Hoechst and DBI and shall be binding upon and
          inure to the benefit of the parties hereto and their respective
          successors and permitted assigns, except that neither this Cooperation
          Agreement nor any of the rights, interests or obligations hereunder
          may be assigned, delegated or transferred, by operation or law, sale
          of stock, change of control or otherwise, voluntarily or
          involuntarily, without the prior written consent of the other party.
          Any such purported assignment, transfer or delegation shall be deemed
          ineffective.

    5.4   Complete Agreement.  The Combination Agreement and this Cooperation
          ------------------                                                 
          Agreement contain the complete agreement between the parties with
          respect to the subject matter herein and supersede any prior


                             COOPERATION AGREEMENT

 
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          understandings, agreements or representations by or between the
          parties, written or oral.

    5.5   Governing Law.  The validity, construction, and enforceability of this
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          Cooperation Agreement shall be governed in all respects by the laws of
          the state of New York, without regard to its conflict of laws rules.

    5.6   Venue. Courts in the federal districts of New York, shall have
          -----
          exclusive venue.

    5.7   No Third-Party Beneficiaries. This Cooperation Agreement is for the
          ----------------------------
          sole benefit of the DBI and Hoechst and their permitted assigns and
          nothing herein expressed or implied shall give or be construed to give
          any person or entity, other than the parties hereto and their
          permitted assigns, any legal or equitable rights hereunder.

    5.8   Order of Precedence. This Cooperation Agreement shall take precedence
          -------------------
          over any Specific Collaboration Agreement, except that the parties may
          agree to waive or modify a term or terms herein by express reference
          in a Specific Collaboration Agreement. Any such reference in a
          Specific Collaboration Agreement shall waive or modify a term or terms
          of this Cooperation Agreement only with respect to the undertakings
          contemplated by that Specific Collaboration Agreement.

    5.9   Survival.  Sections 2.8, 2.9, 2.10 and 5.5, and Article 3 of this
          --------                                                         
          Cooperation Agreement shall survive expiration or termination of this
          Cooperation Agreement.

    5.10  Severability.  If any of the provisions contained in this Cooperation
          ------------                                                         
          Agreement are or become invalid or impracticable for any reason,
          including by virtue of the omission of any other provision, the
          validity of the remaining provisions shall remain unaffected. The
          invalid or impracticable provision shall be substituted or
          supplemented by 


                             COOPERATION AGREEMENT

 
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          provisions that ensure the economic purpose of the invalid or
          impracticable provision as far as possible.

    5.11  Costs.  Each of the parties shall bear its own costs and expenses in
          -----                                                               
          connection with the negotiation and preparation of this Cooperation
          Agreement and any Specific Collaboration Agreement except as otherwise
          set forth herein or in any Specific Collaboration Agreement.

    5.12  Relationship of the Parties.  Neither party shall be considered the
          ---------------------------                                        
          agent or representative of the other party.

    5.13  Counterparts.  This Cooperation Agreement may be executed in multiple
          ------------                                                         
          counterparts all of which taken together shall constitute one and the
          same agreement.

                                 *   *   *   *


                             COOPERATION AGREEMENT

 
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    IN WITNESS WHEREOF, the parties have executed this Cooperation Agreement as
of the Effective Date.


                                DIAGNOSTICS HOLDINGS, INC.


                                By: /s/ John Connaughton
                                    -------------------------------
                                Its:  VICE PRESIDENT-JOHN CONNAUGHTON



                                HOECHST AG


                                By: /s/ Andreas Pollman
                                    ---------------------------------
                                Its:



                                By: 
                                    ---------------------------------
                                Its:


                             COOPERATION AGREEMENT