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                                                                    Exhibit 10.9


                                  REIMBURSEMENT

                                       AND

                               SECURITY AGREEMENT

         THIS AGREEMENT, dated as of December 22, 1999, by BIOSPHERE MEDICAL,
INC., a Delaware corporation (the "Company"), to SEPRACOR, INC. (the "Secured
Party").

                               W I T N E S S E T H

         WHEREAS, BIOSPHERE MEDICAL, INC, a Delaware corporation (the
"Company"), and the Secured Party have entered into a Second Amended and
Restated Revolving Credit Agreement with Fleet National Bank dated as of the
date hereof (as amended from time to time, the "Credit Agreement") pursuant to
which the Secured Party has agreed, subject to the terms and conditions set
forth therein, to guaranty certain revolving loans to the Company (collectively,
the "BioSphere Loans") in accordance with the Guaranty Agreement by Sepracor
Inc. to Fleet National Bank, of even date (the "Guaranty Agreement"), such
BioSphere Loans to be evidenced by the Company's Promissory Note in the original
principal amount of $2,000,000 payable to the order of the Fleet National Bank
(as amended or supplemented from time to time, the "Note"); and

         WHEREAS, the Guaranty Agreement will be beneficial to Biosphere; and

         WHEREAS, the obligation of the Secured Party to guaranty the BioSphere
Loans is subject to the condition, among others, that the Company shall execute
and deliver this Reimbursement and Security Agreement;

         NOW, THEREFORE, in consideration of the willingness of the Secured
Party to guaranty the BioSphere Loans to Fleet National Bank, and for other good
and valuable consideration, receipt of which is hereby acknowledged by the
Company, the Company hereby agrees as follows:

         1.       GRANT OF SECURITY INTEREST. As security for the prompt and
                  complete payment and performance when due of all the Secured
                  Obligations (as defined below), Company hereby pledges,
                  assigns, transfers and grants to Secured Party, a continuing
                  first priority security interest in and to all the following
                  property (collectively, the "Pledged Collateral"): all of the
                  right, title and interest of the Company in, to and under all
                  machinery, equipment, inventory, all accounts, accounts
                  receivable, contract rights, chattel paper, documents, all
                  investment property, securities, security accounts and
                  investment in joint ventures (excluding, in each case, the
                  Company's equity interest in BioSphere Medical France, S.A.
                  (the "French Stock")), all general intangibles, including all
                  royalties and license fees payable to the Company, and
                  including without limitation, all patents, patent
                  applications, copyrights, copyright applications, trademarks,
                  trademark applications, and all goodwill associated therewith,
                  each as it now exists or is


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                  hereafter acquired from time to time, and all amounts from
                  time to time payable under or in connection with any of the
                  Pledged Collateral, and all products and proceeds of the
                  foregoing. This grant covers only the property of the Company
                  and not that of any other entity.

         2.       OBLIGATION TO REIMBURSE; SECURED OBLIGATIONS. The Company
                  hereby agrees that, subject to the provisions of the Guaranty
                  Agreement, it shall immediately reimburse the Secured Party
                  for any and all amounts paid to Fleet National Bank by Secured
                  Party under the Guaranty Agreement (such reimbursement
                  obligation being referred to herein as the "Secured
                  Obligations").

         3.       REPRESENTATIONS, WARRANTIES AND COVENANTS. Company represents,
                  warrants and covenants as follows:

         (a)      NO LIENS. Company is, as of the date hereof, and, as to
                  Pledged Collateral acquired by it from time to time after the
                  date hereof Company will be, the owner of all Pledged
                  Collateral and all French Stock free from any lien or other
                  right, title or interest of any person, and Company shall
                  defend the Pledged Collateral and the French Stock against all
                  claims and demands of all persons at any time claiming any
                  interest therein adverse to Secured Party. Company shall not
                  execute or authorize to be filed in any public office any
                  financing statement (or similar statement or instrument of
                  registration under the law of any jurisdiction) relating to
                  the Pledged Collateral or the French Stock, except financing
                  statements filed or to be filed in respect of and covering the
                  security interest granted hereby by Company.

         (b)      AUTHORIZATION, ENFORCEABILITY. Company has full corporate
                  power, authority and legal right to pledge and grant a
                  security interest in all the Pledged Collateral pursuant to
                  this Agreement, and this Agreement constitutes the legal,
                  valid and binding obligation of Company, enforceable against
                  Company in accordance with its terms.

         4.       PROVISIONS CONCERNING ALL PLEDGED COLLATERAL AND OTHER ASSETS.

         (a)      Company shall, at its own expense, make, execute, endorse,
                  acknowledge, file and/or deliver to Secured Party from time to
                  time such lists and descriptions of the Pledged Collateral,
                  financing statements, powers of attorney and other assurances
                  or instruments and take such further steps relating to the
                  Pledged Collateral and other property or rights covered by
                  this Agreement or the security interest hereby granted
                  (including, without limitation, rights in connection with the
                  French Stock), which Secured Party reasonably deems
                  appropriate or advisable to exercise and enforce its rights
                  and remedies hereunder with respect to any Pledged Collateral
                  (and any subsequent security interest in the French Stock) and
                  to perfect, preserve or protect the security interests in the
                  Pledged Collateral (and any subsequent security interest in
                  the French Stock) created by this Agreement or otherwise.


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         (b)      Company agrees that it will not, except as otherwise expressly
                  permitted by the Credit Agreement (i) sell, convey, assign or
                  otherwise dispose of, or grant any option with respect to, any
                  of the Pledged Collateral or the French Stock, other than
                  sales of inventory in the ordinary course of business or (ii)
                  create or permit to exist any lien upon or with respect to any
                  of the Pledged Collateral or the French Stock, other than the
                  lien and security interest granted to Secured Party under this
                  Agreement or as may be required by the Credit Agreement.

         5.       REMEDIES.

         (a)      OBTAINING THE PLEDGED COLLATERAL UPON EVENT OF DEFAULT. If any
                  event of default shall have occurred and be continuing after
                  any applicable cure period, including without limitation a
                  breach by the Company of any of its obligations hereunder
                  ("Event of Default") then and in every such case, the Secured
                  Party may, at any time or from time to time during the
                  continuance of such Event of Default exercise all rights and
                  remedies of a secured party under the Uniform Commercial Code
                  and may, personally, or by agents or attorneys, immediately
                  take possession of the Pledged Collateral or any part thereof,
                  from Company or any other person who then has possession of
                  any part thereof with or without notice or process of law.

         (b)      WAIVER OF CLAIMS. Company hereby waives, to the fullest extent
                  permitted by applicable law, notice or judicial hearing in
                  connection Secured Party's taking possession of the Pledged
                  Collateral, to the extent permitted by applicable law.

         (c)      PLEDGE OF FRENCH STOCK. Upon the earlier to occur of (i) an
                  Event of Default hereunder, and (ii) the occurrence of a
                  default, and the continuance thereof beyond any applicable
                  cure period, under any agreement with respect to indebtedness
                  for borrowed money (other than purchase money financing and
                  capital leases) to which the Company is a party, including,
                  without limitation, the Credit Agreement, the Company shall
                  immediately pledge to the Secured Party, and grant to the
                  Secured Party a security interest in, the French Stock, and
                  take all actions and execute all documents necessary, at the
                  expense of the Company, to create and perfect the Secured
                  Party's interest in such French Stock.

         6.       APPLICATION OF PROCEEDS. The proceeds of any Pledged
                  Collateral obtained pursuant to the exercise of any remedy set
                  forth in Section 5 shall be applied promptly by Secured Party

                  (i)      FIRST, to the payment of all costs and expenses made
                           or incurred by the Secured Party in connection with
                           the enforcement of the Company's obligations
                           hereunder and the exercise of the Secured Party's
                           rights and remedies;

                  (ii)     SECOND, to the indefeasible payment in full in cash
                           of the unpaid Secured Obligations, and

                  (iii)    THIRD, to Company, or its successors or assigns, or
                           to whomsoever may be


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                           lawfully entitled to receive the same or as a court
                           of competent jurisdiction may direct, of any surplus
                           then remaining from such proceeds.

         7.       SECURED PARTY APPOINTED ATTORNEY-IN-FACT. Company hereby
                  appoints Secured Party its attorney-in-fact with an interest,
                  with full authority in the place and stead of Company and in
                  the name of Company, or otherwise, from time to time in
                  Secured Party's discretion, to take any action and to execute
                  any instrument consistent with terms of this Agreement and the
                  Credit Agreement which the Secured Party may deem necessary or
                  advisable to accomplish the purposes of this agreement. The
                  foregoing grant of authority is a power of attorney coupled
                  with an interest and such appointment shall be irrevocable for
                  the term of this Agreement. Company hereby ratifies all that
                  such attorney shall lawfully do or cause to do be done by
                  virtue hereof.

         8.       TERMINATION; RELEASE. When (i) all the Secured Party's
                  obligations under the Guaranty have been released and
                  terminated AND (ii) all the Secured Obligations have been
                  indefeasibly paid in full and have been terminated, this
                  Agreement shall terminate, and the Secured Party shall
                  promptly release all liens existing in connection herewith.

         9.       GOVERNING LAW. This Agreement, including the validity hereof
                  and the rights and obligations of the parties hereunder, shall
                  be construed in accordance with and governed by the laws of
                  the Commonwealth of Massachusetts.


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IN WITNESS WHEREOF, the Company has executed this Agreement as a sealed
instrument as of the date first above written.

                                   BIOSPHERE MEDICAL, INC.

                                   By: /s/ Robert M. Palladino
                                      ----------------------------------
                                        Name:  Robert M. Palladino
                                        Title: Vice President & Chief
                                        Financial Officer




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