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                                                                    Exhibit 10.8

          Confidential Materials omitted and filed separately with the
      Securities and Exchange Commission. Asterisks denote such omissions.


                      DEVELOPMENT AND PRODUCTION AGREEMENT
                                       FOR
                        ACTIVE PHARMACEUTICAL INGREDIENT


                                     between


                              SIEGFRIED (USA), INC.
                             33 Industrial Park Road
                            Pennsville, NJ 08070 USA

                                       and

                                 SIEGFRIED LTD.
                              Untere Bruhlstrasse 4
                            4800 Zofingen SWITZERLAND

              (hereinafter collectively referred to as "SIEGFRIED")


                                       and


                          MOMENTA PHARMACEUTICALS, INC.
                                43 Moulton Street
                             Cambridge, MA 02138 USA

                     (hereinafter referred to as "MOMENTA")

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                                    RECITALS

This DEVELOPMENT AND PRODUCTION Agreement (the "Agreement") is entered into as
of the last date of signature set forth below (the "Effective Date") by and
between SIEGFRIED and MOMENTA.

WHEREAS, MOMENTA owns certain know-how pertaining to ENOXAPARIN and wishes to
have SIEGFRIED undertake the DEVELOPMENT and PRODUCTION of ENOXAPARIN under the
terms and conditions of this Agreement; and

WHEREAS, SIEGFRIED has expertise in developing and manufacturing active
pharmaceutical ingredients and wishes to undertake the DEVELOPMENT and
PRODUCTION of ENOXAPARIN on behalf of and for MOMENTA under the terms and
conditions of this Agreement;

NOW, THEREFORE, in consideration of the mutual covenants and promises contained
in this Agreement and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, MOMENTA and SIEGFRIED agree as
follows:

1.      DEFINITIONS

For the purpose of this Agreement, the following definitions shall apply:

1.1     "ENOXAPARIN" shall mean the active pharmaceutical ingredient commonly
known as enoxaparin sodium and more specifically described in Appendix A.

1.2     "KNOW-HOW" shall mean information and materials, including, without
limitation, ideas, concepts, discoveries, inventions, developments,
improvements, know-how, expertise, trade secrets, designs, devices, equipment,
process conditions, specifications, algorithms, notation systems, works of
authorship, computer programs, technologies, formulas, techniques, methods,
procedures, assay systems, applications, experimental results, data (including,
without limitation, analytical, toxicological, pharmacological, clinical,
bioequivalence and stability data), documentation, reports, sugars,
polysaccharides, heparinases, enzymes, reagents, glycoproteins, proteins,
peptides, glycoconjugates, primers, plasmids, vectors, expression systems,
cells, cell lines, antibodies, organisms, formulations, chemical compunds and
products, whether patentable or otherwise.

1.3     "MOMENTA KNOW-HOW" shall mean all KNOW-HOW controlled by MOMENTA as of
the date of this Agreement or developed or acquired by MOMENTA during the term,
but not in the performance of, this Agreement that pertains to ENOXAPARIN or
PRODUCT including, without limitation, the DEVELOPMENT of ENOXAPARIN or the
PRODUCTION of ENOXAPARIN or PRODUCT. MOMENTA KNOW-HOW shall not include NEW
KNOW-HOW.

1.4     "MOMENTA IP" shall mean all MOMENTA KNOW-HOW and all patents, patent
applications, copyrights, trade secrets and other intellectual property rights
controlled by MOMENTA covering the MOMENTA KNOW-HOW.

1.5     "SIEGFRIED KNOW-HOW" shall mean all KNOW-HOW (a) controlled by SIEGFRIED
as of the date of this Agreement or developed or acquired by SIEGFRIED during
the term, but not in the performance, of this Agreement that pertains to generic
development or production

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technologies or (b) developed or made and/or reduced to practice by SIEGFRIED
during the performance of this Agreement that pertains solely to generic
development or production technologies. SIEGFRIED KNOW-HOW shall not include NEW
KNOW-HOW.

1.6     "SIEGFRIED IP" shall mean all SIEGFRIED KNOW-HOW and all patents, patent
applications, copyrights, trade secrets and other intellectual property rights
controlled by SIEGFRIED covering the SIEGFRIED KNOW-HOW.

1.7     "NEW KNOW-HOW" shall mean all KNOW-HOW that pertains to ENOXAPARIN or
PRODUCT, the DEVELOPMENT of ENOXAPARIN, or the PRODUCTION of ENOXAPARIN or
PRODUCT that is developed or made and/or reduced to practice by SIEGFRIED
pursuant to this Agreement.

1.8     "NEW IP" shall mean all NEW KNOW-HOW and all patents, patent
applications, copyrights, trade secrets and other intellectual property rights
therein.

1.9     "DEVELOPMENT" shall mean the activities pertaining to the development of
the process for the PRODUCTION of PRODUCT including, without limitation, the
scale-up of the current process and delivery of samples of ENOXAPARIN, that are
described as Phase I - Laboratory under the Scope of Work in Appendix B.

1.10    "PRODUCTION" shall mean the activities pertaining to the production of
PRODUCT including, without limitation, the supply of quantities of PRODUCT, that
are described as Phase II - Pilot Production under the Scope of Work in Appendix
B.

1.11    "PRODUCT" shall mean ENOXAPARIN that meets the SPECIFICATIONS.

1.12    "SPECIFICATIONS" shall mean the specifications set forth in Appendix C
as the same may be amended by MOMENTA in accordance with the terms of this
Agreement.

1.13    "MASTER PRODUCTION RECORD" shall mean the formal set of instructions for
PRODUCTION of PRODUCT.

1.14    "GMP" shall mean those practices in the manufacture of pharmaceutical
products that are recognized as the current good manufacturing practices by the
FDA in accordance with FDA regulations, guidelines and other administrative
interpretations and rulings in connection therewith, including, but not limited
to those regulations cited in 21 C.F.R. Parts 210 and 211 and the International
Conference on Harmonization of Technical Requirements for Registration of
Pharmaceuticals for Human Use, Guidance for Industry Q7A Good Manufacturing
Practice Guidance for Active Pharmaceutical Ingredients, August 2001.

1.15    "ACT" shall mean the Federal Food, Drug and Cosmetics Act, together will
all rules and regulations promulgated thereunder, as the same may be amended
from time to time.

1.16    "FDA" shall mean the United States Food and Drug Administration.

1.17    "REGULATORY AUTHORITIES" shall mean those agencies or authorities
responsible for regulation of PRODUCT in the United States and oversees
including, without limitation, the FDA.

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1.18    "BATCH" shall mean the material resulting from a single manufacturing
order during a specific cycle of PRODUCTION.

1.19    "AFFILIATE" shall mean, with respect to a given party, any company,
corporation or other business entity controlling, controlled by, or under common
control with it at any time during the term of this Agreement. For the purpose
of this definition, the term "control" shall mean the possession of the power to
direct or cause the direction of the management and policies of an entity,
whether through the ownership of voting stock, by contract or otherwise. In the
case of a corporation, the term "control" shall mean the direct or indirect
ownership of at least fifty percent (50%) of the outstanding voting stock.

1.20    "CONFIDENTIAL INFORMATION" shall mean (a) in the case of MOMENTA, the
MOMENTA IP, NEW IP and any and all other information and materials disclosed by
MOMENTA to SIEGFRIED pursuant to the terms of this Agreement and (b) in the case
of SIEGFRIED, the SIEGFRIED IP and any and all other information and materials,
other than the NEW IP, disclosed by SIEGFRIED to MOMENTA pursuant to the terms
of this Agreement.

2.      DEVELOPMENT AND PRODUCTION

2.1     MOMENTA hereby engages SIEGFRIED to undertake the DEVELOPMENT and
PRODUCTION of ENOXAPARIN upon the terms and conditions set forth in this
Agreement and SIEGFRIED hereby accepts such engagement.

2.2     SIEGFRIED shall use commercially diligent efforts to undertake
DEVELOPMENT in accordance with the Scope of Work set forth in Appendix B as
Phase I - Laboratory, with the goal of meeting the time line for the completion
of DEVELOPMENT set forth in Appendix E.

2.3     SIEGFRIED shall use commercially diligent efforts to undertake
PRODUCTION in accordance with the Scope of Work set forth in Appendix B as Phase
II - Pilot Production, with the goal of meeting the time line for the completion
of PRODUCTION set forth in Appendix E and the goal of delivering [**] kilograms
of PRODUCT.

2.4     MOMENTA shall evaluate the samples of ENOXAPARIN delivered as part of
the DEVELOPMENT and shall evaluate the SPECIFICATIONS and MASTER PRODUCTION
RECORD prepared by SIEGFRIED for the PRODUCTION of PRODUCT. In the event that
MOMENTA is not satisfied with the samples of ENOXAPARIN or the SPECIFICATIONS or
MASTER PRODUCTION RECORD for the PRODUCTION of PRODUCT, SIEGFRIED shall continue
to work with MOMENTA on the process for the PRODUCTION of PRODUCT. SIEGFRIED
shall not initiate PRODUCTION until the foregoing activities shall have occurred
and SIEGFRIED shall have received written approval from MOMENTA of the
SPECIFICATIONS and MASTER PRODUCTION RECORD.

2.5     Laboratory studies conducted as part of the DEVELOPMENT may, but need
not, be performed in compliance with GMP. All DEVELOPMENT and PRODUCTION
associated with the actual manufacture of the [**] kilograms of PRODUCT shall be
performed in compliance with all applicable laws, regulations and rules
including, without limitation, GMP and the ACT. Further, all PRODUCT shall meet
the SPECIFICATIONS and all PRODUCTION shall be in accordance with the MASTER
PRODUCTION RECORD.

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2.6     SIEGFRIED shall perform all DEVELOPMENT and PRODUCTION at its facility
located in Pennsville, New Jersey.

2.7     PRODUCT shall be used by MOMENTA for stability, preclinical, clinical
and other development purposes.

3.      TRANSFER OF INFORMATION AND MATERIALS

3.1     MOMENTA shall be responsible for providing SIEGFRIED with such MOMENTA
KNOW-HOW as is reasonably necessary for SIEGFRIED to conduct the DEVELOPMENT and
PRODUCTION including, without limitation, the existing laboratory-scale process
for the PRODUCTION of ENOXAPARIN and the analytical methods for the PRODUCTION
of PRODUCT.

3.2     SIEGFRIED shall be responsible for the procurement of all raw materials
as are required for SIEGFRIED to conduct the DEVELOPMENT and PRODUCTION,
provided that MOMENTA shall be responsible for supplying SIEGFRIED, at no cost,
with the necessary quantities of heparin for DEVELOPMENT and with [**] kilograms
of heparin for PRODUCTION.

3.3     Upon any expiration or termination of this Agreement, for whatever
reason, SIEGFRIED shall forward to MOMENTA, upon MOMENTA's request, any
quantities of raw material supplied by MOMENTA or purchased by SIEGFRIED
pursuant to this Agreement, any quantities of ENOXAPARIN or PRODUCT, and any
quantities of any other material produced pursuant to this Agreement, such as
materials constituting work-in-progress. Notwithstanding the foregoing,
SIEGFRIED shall be entitled to retain such samples of the foregoing as are
required by law or are required in order for SIEGFRIED to comply with its
standard operating procedures.

4.      COLLABORATION AND REPORTING

4.1     SIEGFRIED shall perform the DEVELOPMENT and PRODUCTION in collaboration
with MOMENTA and shall keep MOMENTA regularly informed with respect to the
status of the DEVELOPMENT and PRODUCTION. Further, SIEGFRIED shall provide
MOMENTA with monthly written reports in a brief summarized form depicting the
progress of the work according to Appendices B and E.

4.2     Each party shall appoint one representative to be responsible for the
collaboration under this Agreement and all day-to-day communication between the
parties under this Agreement shall be addressed to such representatives. Any
report, approval or notice required or permitted to be given under or in
connection with this Agreement shall be deemed to have been sufficiently given
if in writing and sent by certified or registered mail, return receipt
requested, postage prepaid, sent by a nationally recognized overnight courier
service, or sent by hand delivery, to the representative for such party at the
address set forth below for such party. If a party changes its representative or
address, written notice shall be given promptly to the other party of the new
representative or address. Notice shall be deemed given on the third business
day after being sent in the case of delivery by mail, on the first business day
after being sent in the case of delivery by overnight courier, and on the date
of delivery in the case of delivery by hand.

The addresses of the parties and representatives are as follows:

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If to MOMENTA:       Momenta Pharmaceuticals, Inc.
                     43 Moulton Street
                     Cambridge, MA 02138

                     Representative: Joseph E. Tyler
                     E-Mail: jtyler@momentapharma.com

If to SIEGFRIED:     Siegfried (USA), Inc.
                     33 Industrial Park Road
                     Pennsville, NJ 08070

                     Representative: Scott M. Powers
                     E-Mail: scott.powers@siegfried-usa.com

5.      DOCUMENTATION AND RECORD KEEPING

5.1     With respect to each BATCH of PRODUCT, SIEGFRIED shall maintain and
submit to MOMENTA copies of the completed batch record, deviation reports,
out-of-specification records, investigation reports, in-process control raw
data, analytical data, certificates of analysis and MASTER PRODUCTION RECORD.

5.2     SIEGFRIED shall retain all raw data for thirteen (13) years from the
expiration or termination of this Agreement. After this period SIEGFRIED shall,
upon the timely request of MOMENTA within thirty (30) days after notification
from SIEGFRIED, forward such data to MOMENTA. Otherwise SIEGFRIED shall destroy
such raw data.

6.      QUALITY ASSURANCE AUDITS AND INSPECTIONS

6.1     SIEGFRIED's quality assurance group shall closely monitor and report on
the DEVELOPMENT of ENOXAPARIN and the PRODUCTION of PRODUCT in order to verify
compliance with GMP and the ACT.

6.2     MOMENTA shall have the right to request up to two (2) quality assurance
audits of the DEVELOPMENT of ENOXAPARIN and the PRODUCTION of PRODUCT in order
to verify compliance of DEVELOPMENT and PRODUCTION in accordance with the terms
of this Agreement. More frequent audits shall be permitted by SIEGFRIED in the
case of deficiencies as described Sections 13.1 and 13.2. All visits shall be
during normal business hours, shall not, either individually or when taken
together with all other such visits, unreasonably interrupt the operation of
SIEGFRIED, and shall be at the expense of MOMENTA. Further, all visiting
employees and consultants of MOMENTA shall have executed an appropriate
non-disclosure agreement or otherwise be under an obligation of confidentiality
consistent with Article 8 and shall comply at all times with all security and
other personnel and visitor procedures of SIEGFRIED.

6.3     Unless required by law, SIEGFRIED shall have no contact or communication
with any REGULATORY AUTHORITY regarding the DEVELOPMENT or PRODUCTION without
the prior written consent of MOMENTA and MOMENTA shall be solely responsible for
all such contacts and communications. In the event that SIEGFRIED receives any
contact or communication

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from any REGULATORY AUTHORITY pertaining to the DEVELOPMENT or PRODUCTION,
SIEGFRIED shall notify MOMENTA immediately and shall provide MOMENTA with copies
of any tangible manifestations of any such contact or communication within one
(1) business day thereafter. SIEGFRIED shall consult with MOMENTA regarding the
response to any such contact or communication and shall permit MOMENTA to
control and/or participate in such response. SIEGFRIED shall allow inspections
by REGULATORY AUTHORITIES of the DEVELOPMENT and PRODUCTION. In the event that
the DEVELOPMENT or PRODUCTION is inspected by a REGULATORY AUTHORITY, SIEGFRIED
shall inform MOMENTA prior to such inspection if at all possible or, if not
possible, immediately following such inspection.

7.      RIGHTS, INVENTIONS AND PATENTS

7.1     All MOMENTA IP shall be and remain the exclusive property of MOMENTA.
All SIEGFRIED IP shall be and remain the exclusive property of SIEGFRIED. All
NEW IP shall be "works made for hire" and the exclusive property of MOMENTA.
Further, all records of work performed by SIEGFRIED under this Agreement and all
reports required to be delivered by SIEGFRIED to MOMENTA under this Agreement
shall be "works made for hire" and the exclusive property of MOMENTA.
Notwithstanding the foregoing, solely to the extent necessary to comply with
applicable laws and regulations, SIEGFRIED shall have the right to keep one (1)
copy, or if so required one (1) original, of such records and reports.

7.2     MOMENTA, or its designee, shall have the sole right to file patent
applications relating to inventions included in the NEW KNOW-HOW. In the event
that MOMENTA, or its designee, seeks such patent protection, MOMENTA, or its
designee, shall bear the costs, including, but not limited to, attorneys fees,
associated with preparing, filing and prosecuting such patent applications and
for maintaining such patent protection as may be granted. In the event that
MOMENTA, or its designee, seeks such patent protection, SIEGFRIED shall provide
MOMENTA with reasonable assistance to obtain and defend such patent protection
at MOMENTA's expense.

7.3     If, during the course of this Agreement, SIEGFRIED, or any of its
employees or consultants, develops or makes and/or reduces to practice any item,
including, without limitation, any invention, included in the NEW KNOW-HOW,
SIEGFRIED hereby irrevocably assigns to MOMENTA all right, title and interest
it, or any of its employees, consultants and permitted subcontractors, may have
in such items included in the NEW KNOW-HOW.

7.4     SIEGFRIED further agrees that, upon request by MOMENTA and at MOMENTA's
expense, SIEGFRIED shall promptly execute, acknowledge or deliver any papers
deemed reasonably necessary by MOMENTA to document, enforce, protect, and
otherwise perfect such rights of MOMENTA, including, without limitation, all
documents necessary to obtain or perfect any intellectual property protection
and/or to effect an assignment of ownership of the same to MOMENTA.

7.5     SIEGFRIED represents that it has or will have agreements with all
employees, consultants and permitted subcontractors of SIEGFRIED who participate
in the DEVELOPMENT or PRODUCTION which effectively vest in SIEGFRIED any and all
rights which such persons or entities might otherwise have in the results of
their work and are adequate to permit SIEGFRIED to transfer such rights to
MOMENTA in accordance with this Article 7.

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7.6     MOMENTA hereby grants to SIEGFRIED a non-exclusive, non-sublicensable,
royalty-free license under the MOMENTA IP and NEW IP to conduct the DEVELOPMENT
and PRODUCTION during the term of this Agreement.

7.7     SIEGFRIED hereby grants to MOMENTA a non-exclusive, worldwide,
irrevocable, sublicensable, royalty-free license under the SIEGFRIED IP to
develop, make, have made, use, sell, have sold, offer for sale, import and have
imported ENOXAPARIN or PRODUCT and to otherwise exploit the NEW IP.

7.8     SIEGFRIED hereby agrees, during the term of this Agreement and for a
period of [**] years after the expiration or termination of this Agreement,
regardless of the cause of such expiration or termination, to work exclusively
with MOMENTA with respect to the DEVELOPMENT of ENOXAPARIN and/or the PRODUCTION
of ENOXAPARIN and PRODUCT.

7.9     To the extent that the NEW IP has application to products other than
unfractionated or low molecular weight heparin products, MOMENTA hereby grants
to SIEGFRIED a non-exclusive, worldwide, irrevocable, non-sublicensable,
royalty-free license under the NEW IP to develop, make, have made, use, sell,
have sold, offer for sale, import and have imported products that are not
unfractionated heparin or a low molecular weight heparin. For purposes of
clarity, the foregoing shall not be construed to constitute an implied license
to any MOMENTA IP.

8.      CONFIDENTIALITY

8.1     Each party agrees to retain in strict confidence and not to disclose,
divulge or otherwise communicate to any other person or entity any CONFIDENTIAL
INFORMATION of the other party, whether disclosed prior to, or after the date
hereof, and further agrees not to use any such CONFIDENTIAL INFORMATION for any
purpose, except pursuant to, and in order to carry out, the terms and objectives
of this Agreement, provided that each party may disclose CONFIDENTIAL
INFORMATION of the other party to the officers, directors, employees, agents,
consultants, permitted subcontractors or other representatives of the receiving
party or its AFFILIATES (the "Representatives"), who, in each case, need to know
such CONFIDENTIAL INFORMATION for purposes of the implementation and performance
by the receiving party of this Agreement and will use such CONFIDENTIAL
INFORMATION only for such limited purposes.

8.2     Each party agrees to use at least the same standard of care as it uses
to protect proprietary or CONFIDENTIAL INFORMATION of its own of comparable
sensitivity and to exercise every reasonable precaution to prevent and restrain
the unauthorized disclosure of such CONFIDENTIAL INFORMATION by any of its
Representatives.

8.3     Each party warrants that each of its Representatives to whom any
CONFIDENTIAL INFORMATION is revealed shall previously have been informed of the
confidential nature of the CONFIDENTIAL INFORMATION and shall have agreed to be
bound by the terms and conditions of this Article 8 applicable to the receiving
party.

8.4     The provisions of Section 8.1 shall not apply to any CONFIDENTIAL
INFORMATION disclosed hereunder which:
        a)      was known by the receiving party prior to its disclosure to the
receiving party by the other party, as evidenced by the prior written records of
the receiving party; or

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        b)      either before or after the date of disclosure to the receiving
party by the other party is lawfully disclosed to receiving party by an
independent, unaffiliated third party rightfully in possession of the
CONFIDENTIAL INFORMATION, provided that disclosure and use is in conformity with
the obligations of confidentiality and non-use imposed by such third party; or
        c)      either before or after the date of disclosure to the receiving
party by the other party becomes published or generally known to the public
through no fault or omission on the part of the receiving party or its
Representatives; or
        d)      is developed independently by the receiving party without use of
CONFIDENTIAL INFORMATION of the other party, as evidenced by the written records
of the receiving party; or
        e)      is required to be disclosed by the receiving party to comply
with applicable laws, to defend or prosecute litigation, or to comply with
governmental laws or regulations, provided that the receiving party provides
prior written notice of such disclosure to the other party and takes reasonable
and lawful actions to avoid and/or minimize the degree of such disclosure.

8.5     Notwithstanding anything herein to the contrary, the parties agree that
disclosure and use by MOMENTA or SIEGFRIED of CONFIDENTIAL INFORMATION of the
other party pursuant to any of the licenses granted in Sections 7.6 through 7.8
shall not be a violation of any term or condition contained in this Article 8,
provided that such disclosure or use is reasonably necessary in order to exploit
the applicable license granted.

8.6     Except as may be required by law or regulation, or in response to a
valid subpoena or other judicial order, neither party shall disclose the terms
of this Agreement without the prior written consent of the other party, except
that the parties may disclose the terms of this Agreement to their accountants
and attorneys, provided any such attorney or accountant agrees to be bound by
the confidentiality obligations of this Section 8.6.

8.7     Except as otherwise set forth in this Agreement, nothing herein shall be
construed as giving either party any right, title, interest in or ownership of
the CONFIDENTIAL INFORMATION of the other party. For the purposes of this
Agreement, any specific item disclosed as part of CONFIDENTIAL INFORMATION shall
not be deemed to be in the public domain or in the prior possession of the
receiving party merely because it is embraced by more general information in the
public domain or by more general information in the prior possession of the
receiving party.

8.8     The confidentiality obligations of the parties contained in this
Article 8 shall remain binding on both parties during the term of this Agreement
and for a period of fifteen (15) years after the expiration or termination of
this Agreement, regardless of the cause of such expiration or termination. The
parties acknowledge that any breach of this Article 8 will constitute
irreparable harm, and that the non-breaching party shall be entitled to specific
performance or injunctive relief to enforce this Article 8 in addition to
whatever remedies such party may otherwise be entitled to at law or in equity.

9.      TERMINATION

9.1     This Agreement shall commerce upon the Effective Date and, unless
terminated sooner in accordance with the terms and conditions provided herein,
shall remain in full force and effect until the date of the delivery and
acceptance of the [**] kilograms of PRODUCT by MOMENTA.

9.2     Either party may terminate this Agreement immediately by providing
written notice to the other party upon the occurrence of any of the following
events:

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        a)      the other party breaches a material obligation of this Agreement
and, after written notification from the non-breaching party, fails to remedy
the breach within fifteen (15) days of such written notification; or
        b)      either party reasonably determines that, for valid scientific or
technical reasons, the goals for the DEVELOPMENT or PRODUCTION cannot be
achieved within the parameters or timelines agreed to in Appendices B and E and
the parties cannot agree on a modification of such goals, parameters or
timelines within thirty (30) days of the date of the determination, it being
understood that each party shall be obligated to use good faith efforts to agree
on as minimal a modification of such goals, parameters or timelines as is
reasonably required by the scientific or technical obstacle; or
        c)      solely to the extent permitted by law, the other party opens
bankruptcy proceedings, goes into receivership, or allows its creditors to place
the company in receivership.

9.3     MOMENTA may terminate this Agreement, at any time, upon the giving of
thirty (30) days prior written notice to SIEGFRIED.

9.4     Upon any termination of this Agreement, the parties shall determine the
total amount of (a) the cost of all raw materials purchased by SIEGFRIED for
purposes of DEVELOPMENT and PRODUCTION plus (b) a reasonable estimate of the
cost of the labor associated with the proportion of the DEVELOPMENT and
PRODUCTION performed up to the date of the determination in the case of a
termination pursuant to clause (b) of Section 9.2 or up to the date of the
termination in the case of all other terminations of this Agreement (the "Actual
Cost"). For purposes of the foregoing calculation, fifty percent (50%) of the
fee set forth in Section 10.1 shall be attributed to the DEVELOPMENT and fifty
percent (50%) of the fee set forth in Section 10.1 shall be attributed to the
PRODUCTION. In the event of a termination by MOMENTA pursuant to clause (b) of
Section 9.2 or Section 9.3 or a termination by SIEGFRIED, subject to SIEGFRIED's
compliance with Section 3.3, SIEGFRIED shall be entitled to retain or receive
the Actual Cost. In determining whether an actual payment shall be due SIEGFRIED
from MOMENTA, all amounts previously paid by MOMENTA pursuant to Section 10.1
for DEVELOPMENT and PRODUCTION shall be taken into account. In the event that
MOMENTA shall have previously paid SIEGFRIED an amount greater than the Actual
Cost, SIEGFRIED shall pay MOMENTA an amount equal to the difference between the
amount previously paid by MOMENTA and the Actual Cost. In the event of a
termination by MOMENTA pursuant to clause (a) or (c) of Section 9.2, SIEGFRIED
shall not be entitled to any further payments from MOMENTA but, subject to
SIEGFRIED's compliance with Section 3.3, shall be entitled to retain all amounts
previously paid by MOMENTA pursuant to Section 10.1 for DEVELOPMENT and
PRODUCTION unless MOMENTA shall have previously paid SIEGFRIED an amount greater
than the Actual Cost. In any such case, SIEGFRIED shall pay MOMENTA an amount
equal to the difference between the amount previously paid by MOMENTA and the
Actual Cost.

9.5     All rights and obligations as set forth in Sections 3.3, 5.2, 7.1, 7.2,
7.3, 7.4, 7.5, 7.7, 7.8, 7.9, 9.4, 13.3, 13.4 and 13.5 and Articles 8 and 12
shall continue irrespective of any expiration or termination of this Agreement.

9.6     The waiver by the parties of any breach, covenant or condition herein
contained shall not be deemed to be a waiver of any subsequent breach of the
same or any other term, covenant or condition herein.

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10.     PAYMENT AND DELIVERIES

10.1    MOMENTA shall pay SIEGFRIED a total fee of Four Hundred Twenty-Five
Thousand U.S. Dollars ($425,000) for the DEVELOPMENT and PRODUCTION. Such fee
shall become due in accordance with the timetable set forth in Appendix D.
SIEGFRIED shall invoice MOMENTA as payments become due and MOMENTA shall pay
such invoices within thirty (30) days thereafter.

10.2    If, during the course of DEVELOPMENT, it becomes reasonably apparent to
SIEGFRIED that (a) circumstances exist which could not have been foreseen by the
parties or which were excluded from the assumptions made by both parties in
agreeing to the fee set forth in Section 10.1 and (b) such circumstances render
the completion of the DEVELOPMENT and PRODUCTION materially more costly than had
been foreseen by the parties, SIEGFRIED shall notify MOMENTA in writing. Upon
receipt of such notification, the parties shall use good faith efforts to agree
on as minimal a modification of the fee set forth in Section 10.1 as is
reasonably required by the unforseen or changed circumstance. If the parties
agree on an associated increase in cost, SIEGFRIED shall proceed with the
DEVELOPMENT and PRODUCTION. If the parties do not agree on an associated
increase in cost, SIEGFRIED shall have the right to proceed with DEVELOPMENT and
PRODUCTION or treat the circumstances as a technical obstacle and terminate this
Agreement in accordance with clause (b) of Section 9.2.

10.3    Delivery of ENOXAPARIN and PRODUCT shall be "ex works PENNSVILLE, NEW
JERSEY" as defined in the current INCOTERMS.

11.     SUBCONTRACTING

11.1    SIEGFRIED shall not be entitled to engage any subcontractor for the
DEVELOPMENT or the PRODUCTION without the prior written consent of MOMENTA. If a
subcontractor is appointed, SIEGFRIED shall be responsible for all work
performed by such subcontractor. The parties acknowledge in advance that
SIEGFRIED does not have the in-house capability to assay for certain biological
activities for quality control purposes, and that MOMENTA and SIEGFRIED will
mutually agree on appropriate third party subcontractors to conduct such assays
on behalf of SIEGFRIED.

11.2    In the event that MOMENTA requests a modification of the process
pertaining to the DEVELOPMENT of ENOXAPARIN or the PRODUCTION of PRODUCT for
which SIEGFRIED believes the expertise of a subcontractor is reasonably
necessary and MOMENTA is unwilling to approve such a subcontractor, SIEGFRIED
shall have the right to treat such refusal as a technical obstacle and terminate
this Agreement pursuant to clause (b) of Section 9.2.

11.3    MOMENTA shall be entitled to join any audit conducted by SIEGFRIED of a
supplier of raw material or of a subcontractor.

12.     WARRANTIES

12.1    Each party represents and warrants that, as of the effective date of
this Agreement, it is not a party to any agreement, contract, arrangement or the
like with any third party, or under any obligation or restriction, including,
without limitation, pursuant to its charter documents or by laws, which in any
way limits or conflicts with its ability to fulfill any of its obligations under
this Agreement.

<Page>

12.2    SIEGFRIED makes no representation or warranty that the processes used in
developing or producing ENOXAPARIN or PRODUCT or that the production, use or
importation of ENOXAPARIN or PRODUCT, would not infringe any patent or other
proprietary right belonging to a third party. Notwithstanding the foregoing,
SIEGFRIED represents and warrants to MOMENTA that, as of the effective date of
this Agreement, it has not received any notice from any third party that the
practice of the SIEGFRIED IP infringes any patent or other proprietary rights of
any third party and SIEGFRIED has no knowledge of any third party patent or
proprietary rights that might be infringed by the practice of the SIEGFRIED IP.
Further, SIEGFRIED represents and warrants to MOMENTA that it will not knowingly
use any infringing or misappropriated SIEGFRIED IP in the DEVELOPMENT or
PRODUCTION.

13.     PRODUCT QUALITY, INDEMNIFICATION AND INSURANCE

13.1    In the case of a material error by SIEGFRIED which results in an
inability to achieve the goals for the DEVELOPMENT or PRODUCTION within the
parameters or timelines agreed to in Appendices B and E, SIEGFRIED shall inform
MOMENTA immediately and exercise diligent efforts to correct the error so that
the goals for the DEVELOPMENT and PRODUCTION are achieved within the parameters
agreed to in Appendix B as soon as possible thereafter.

13.2    In the event that MOMENTA believes it is justified in rejecting PRODUCT
because it does not meet the requirements of Section 2.5, MOMENTA shall inform
SIEGFRIED accordingly with a written notice delivered within forty-five (45)
days from the date of receiving the PRODUCT. In any such case, the parties shall
repeat the disagreed upon sampling and analysis. Should MOMENTA still believe it
is justified in rejecting the PRODUCT following such repeated sampling and
analysis, MOMENTA shall have the right to engage an independent third party to
perform the disagreed upon sampling and analysis. Should the results show that
the PRODUCT does not meet the requirements of Section 2.5, SIEGFRIED shall
exercise diligent efforts to replace the PRODUCT as soon as possible thereafter
and shall be responsible for the cost of the replacement raw materials (other
than the heparin) and the sampling and analysis conducted by the independent
third party.

13.3    MOMENTA shall, at all times during the term of this Agreement and
thereafter, indemnify, defend and hold harmless SIEGFRIED, and its directors,
officers, employees and AFFILIATES (the "Other SIEGFRIED Indemnified Parties"),
from and against any and all third party product liability claims, proceedings,
demands and liabilities, of any kind whatsoever, including legal expenses and
reasonable attorneys' fees, arising out of the death of or injury to any person
or out of any damage to property resulting from the production, use or
consumption of any ENOXAPARIN or PRODUCT developed or produced pursuant to this
Agreement, excluding any such losses resulting from the failure of the PRODUCT
to meet the requirements of Section 2.5 or the negligence or misconduct of
SIEGFRIED.

13.4    SIEGFRIED shall, at all times during the term of this Agreement and
thereafter, indemnify, defend and hold harmless MOMENTA, and its directors,
officers, employees and AFFILIATES (the "Other MOMENTA Indemnified Parties"),
from and against any and all third party product liability claims, proceedings,
demands and liabilities, of any kind whatsoever, including legal expenses and
reasonable attorneys' fees, arising out of the death of or injury to any person
or out of any damage to property resulting from the production, use or
consumption of any ENOXAPARIN or PRODUCT developed or produced pursuant to this
Agreement where

<Page>

such losses result from the failure of the PRODUCT to meet the requirements of
Section 2.5 or the negligence or misconduct of SIEGFRIED.

13.5    Prior to the first use in humans of any ENOXAPARIN or PRODUCT developed
or produced pursuant to this Agreement, each party shall obtain and carry in
full force and effect commercial general liability insurance, including clinical
trial product liability insurance, which shall protect the other party with
respect to events covered by Sections 13.3 and 13.4. Such insurance shall be
written by a reputable insurance company authorized to do business in the United
States of America, shall list the other party as an additional named insured
thereunder, and shall require thirty (30) days written notice to be given to the
other party prior to any cancellation or material change thereof. The limits of
such insurance shall not be less than one million dollars ($1,000,000) per
occurrence with an aggregate of three million dollars ($3,000,000) for personal
injury, including death, and one million dollars ($1,000,000) per occurrence
with an aggregate of three million dollars ($3,000,000) for property damage.
Each party shall provide the other party with a certificate of insurance
evidencing the same.

13.6    MOMENTA shall, at all times during the term of this Agreement and
thereafter, indemnify, defend and hold harmless SIEGFRIED and the Other
SIEGFRIED Indemnified Parties, from and against any and all third party
liability claims, proceedings, demands and liabilities, of any kind whatsoever,
including legal expenses and reasonable attorneys' fees, arising out of any
alleged infringement of any patent or other intellectual property right held by
a third party in connection with the DEVELOPMENT or PRODUCTION or the use or
importation of any ENOXAPARIN or PRODUCT developed or produced pursuant to this
Agreement, excluding any such losses resulting from a breach by SIEGFRIED of the
representation and warranty set forth in Section 12.2.

13.7    SIEGFRIED shall, at all times during the term of this Agreement and
thereafter, indemnify, defend and hold harmless MOMENTA and the Other MOMENTA
Indemnified Parties, from and against any and all third party liability claims,
proceedings, demands and liabilities, of any kind whatsoever, including legal
expenses and reasonable attorneys' fees, arising out of any alleged infringement
of any patent or other intellectual property right held by a third party in
connection with the DEVELOPMENT or PRODUCTION or the use or importation of any
ENOXAPARIN or PRODUCT developed or produced pursuant to this Agreement where
such losses resulting from a breach by SIEGFRIED of the representation and
warranty set forth in Section 12.2.

13.8    If party or any of its associated indemnified parties intends to claim
indemnification under this Article 13, such party shall promptly notify the
other party in writing of the action, claim or other matter in respect of which
such party or any of its associated indemnified parties intends to claim such
indemnification. Such party shall permit, and, in order for any of its
associated indemnified parties to be indemnified pursuant to this Article 13,
shall cause such associated indemnified parties to permit, the other party to
solely control the defense and/or settlement of such action, claim or other
matter. No such action, claim or other matter shall be settled by such party or
any of its associated indemnified parties without the prior written consent of
the other party. Such party and its associated indemnified parties who seek to
be indemnified pursuant to this Article 13 shall fully cooperate with the other
party and its legal representatives in the investigation and defense of any
action, claim or other matter covered by the indemnification obligations of this
Article 13. Such party and its associated indemnified parties shall have the
right, but not the obligation, to be represented in such defense by counsel of
their own selection and at their own expense.

<Page>

13.9    In the event a claim is based partially on an indemnified claim and
partially on a non-indemnified claim, or based partially on a claim indemnified
by one party and partially on a claim indemnified by the other party, any
payments in connection with such claims are to be apportioned between the
parties in accordance with the degree of cause attributable to each party.

14.     MISCELLANEOUS

14.1    The working language for DEVELOPMENT and PRODUCTION under this
Agreement, the execution of this Agreement, and the interpretation of the terms
of this Agreement shall be the English language.

14.2    Neither this Agreement, nor any of the rights or obligations hereunder,
may be assigned by either party without the prior written consent of the other
party, except that (a) either party may assign this Agreement, whether by
operation of law, contract, or otherwise, without such consent, to a third party
who acquires all or substantially all of the assets of the assigning party or at
least 50% of the capital stock of the assigning party, whether by sale of stock,
merger or similar transaction, or otherwise acquires all or substantially all of
the business of the assigning party and (b) MOMENTA may assign this Agreement,
without such consent, to a third party who enters into an agreement with MOMENTA
pertaining to the development and commercialization of ENOXAPARIN, provided in
each instance that such third party agrees to be subject to and bound by all of
the terms and conditions of this Agreement. Notwithstanding the foregoing, in
the case of an assignment by MOMENTA to a major pharmaceutical company, such
major pharmaceutical company shall be entitled to self-insure under
Section 13.5. Any purported assignment in contravention of this Section 14.2
shall be null and void and of no effect.

14.3    Either party shall be excused from performing its obligation under this
Agreement if its performance is delayed or prevented by any cause beyond such
party's control, including but not limited to, act of God, fire, explosion,
weather, disease, war, insurrection, civil strife, riots, government action, or
power failure. Performance shall be excused only to the extent of and during the
reasonable continuance of such disability. Any deadline or time for performance
specified in an appendix to this Agreement that falls due during or subsequent
to the occurrence of any of the disabilities referred to herein shall be
automatically extended for a period of time equal to the period of such
disability. SIEGFRIED shall immediately notify MOMENTA if, by reason of any of
the disabilities referred to herein, SIEGFRIED is unable to meet any deadline or
time for performance specified in an appendix to this Agreement. The foregoing
shall not be construed to alter MOMENTA's rights under Section 9.3.

14.4    Nothing herein, or in any appendix to this Agreement, shall be deemed or
construed to constitute or create between the parties hereto a partnership,
joint venture, agency, or other relationship other than as expressly set forth
herein. Neither party shall be responsible for the acts or omissions of the
other party, and neither party will have authority to speak for, represent or
obligate the other party in any way without prior written authority from the
other party.

14.5    This Agreement and the appendices to this Agreement, which appendices
are deemed to be a part of this Agreement for all purposes, contain the full
understanding of the parties with respect to the subject matter hereof and
supersede all prior understandings and writings relating thereto. No waiver,
alteration or modification of any of the provisions hereof shall be binding
unless made in writing and signed by the parties.

<Page>

14.6    In the event that any term of this Agreement shall violate any
applicable statute, ordinance or rule of law in any jurisdiction in which it is
used, or otherwise be unenforceable, such provision shall be ineffective to the
extent of such violation without invalidating any other provision hereof.

14.7    Each party represents and warrants to the other that it has the legal
power, authority and right to enter into this Agreement and to perform its
respective obligations set forth herein. This Agreement has been duly executed
and delivered by each party and constitutes the valid and binding obligation of
such party, enforceable against such party in accordance with its terms.

14.8    This Agreement may be executed in counterparts, including signatures by
facsimile, each of which shall be deemed an original, but all of which together
shall constitute but one and the same Agreement.

14.9    This Agreement shall be governed and interpreted in accordance with the
laws of the State of New Jersey.


In WITNESS WHEREOF, the parties have had this Agreement signed by their duly
authorized representatives, all as of the effective date.


SIEGFRIED (USA), INC.                           SIEGFRIED LTD

By: /S/ DONALD D. BELL                           By: /s/ DENNIS P. BAUER
   --------------------------                      -----------------------------

Title:   President                              Title: VP - Business Areas (USA)
      -----------------------                         --------------------------

Date:    Oct. 6, 2003                           Date:  October 3, 2003
     ------------------------                        ---------------------------


MOMENTA PHARMACEUTICALS, INC.

By: /s/ JOSEPH E. TYLER
   --------------------------

TITLE: Vice President
      ---------------------------

DATE:  October 10, 2003
      ---------------------------

<Page>

                                   APPENDIX A.

                            Description of ENOXAPARIN


Product Name: Enoxaparin Sodium


Molecular formula: [**]


Molecular weight: [**]


Structural formula:


                                      [**]


CAS - number: [**]

<Page>

                                   APPENDIX B.

                           DEVELOPMENT and PRODUCTION


GENERAL

The following Scope of Work is based on MOMENTA's Request for Proposal for the
development and production of ENOXAPARIN dated February 14, 2003, the process
described therein, and additional technical information provided by MOMENTA.
Unforeseen circumstances and changes in the assumptions of the parties are dealt
with in Sections 9.2, 10.2 and 11.2 of the Agreement.

ASSUMPTIONS

The following set of assumptions form the basis for the Scope of Work:

The overall process yield will be [**].

SIEGFRIED will conduct [**].

SIEGFRIED will conduct [**].

SIEGFRIED will conduct [**].

SIEGFRIED will conduct [**].


SCOPE OF WORK

PHASE I - LABORATORY

[**] provided by MOMENTA.

[**] provided by MOMENTA and implement [**].

Identify [**].

Develop [**].

Deliver [**].

Characterize [**].

<Page>

Conduct safety testing on [**].

Screen [**].

Provide laboratory report on the development work conducted and the final
laboratory scale process.


PHASE II - PILOT PRODUCTION

Prepare [**] in accordance with the [**].

[**] with the exception of [**].

Produce [**].

[**], provide MOMENTA with all [**].

Conduct [**].

Provide [**].

Provide project summary report following completion of pilot production.

<Page>

                                   APPENDIX C.

                       Draft Specifications for ENOXAPARIN

<Table>
<Caption>
       TEST                         METHOD                 EP SPECIFICATIONS            USP SPECIFICATIONS
----------------------------------------------------------------------------------------------------------------
<S>                           <C>                     <C>                           <C>
Description                   Visual                  [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]

[**]                          [**]                    [**]                          [**]
</Table>

<Page>

                                   APPENDIX D.

                               Pricing Assumptions

-    Heparin will be provided to SIEGFRIED at no cost to SIEGFRIED.

-    The cost for the [**] will be $[**] per kilogram.

-    The third party cost associated with the performance of quality control
     assays of biological activities is excluded from the total due SIEGFRIED.

PAYMENT SCHEDULE:

-    [**] percent ([**]%) of the total cost due under Section 10.1 will be due
     on November 1, 2003, provided that Momenta and Siegfried may mutually agree
     to an acceleration of the initial work contemplated under this Agreement
     and an earlier payment of this amount.

-    [**] percent ([**]%) of the total cost due under Section 10.1 of the
     Agreement will be due [**].

-    The balance of the total due under Section 10.1 of the Agreement will be
     due upon completion of PRODUCTION.

<Page>

                                   APPENDIX E:

                                    Schedule


The following completion dates are conditioned upon MOMENTA's fulfilment of its
obligations to SIEGFRIED under Sections 3.1 and 3.2 of the Agreement on a timely
basis.

PHASE I COMPLETION DATE:     [**] from execution of the Agreement.


PHASE II COMPLETION DATE:    [**] from approval of MASTER PRODUCTION RECORD and
                             SPECIFICATIONS by MOMENTA

<Page>

                          Momenta Pharmaceuticals, Inc.
                                43 Moulton Street
                         Cambridge, Massachusetts 02138

                                    February 14, 2004

Mr. Scott M. Powers
Siegfried (USA), Inc.
33 Industrial Park Road
Pennsville, NJ 08070

Dear Scott:

Reference is made to the Development and Production Agreement for Active
Pharmaceutical Ingredient between Siegfried (USA), Inc. and Siegfried Ltd.
("SIEGFRIED") and Momenta Pharmaceuticals, Inc. ("MOMENTA") dated October 10,
2003 (the "Agreement"). Capitalized terms used herein and not otherwise defined
shall have the meanings given such terms in the Agreement.

MOMENTA hereby engages SIEGFRIED to undertake the additional development work
set forth on Appendix A to this Letter Agreement (the "ADDITIONAL DEVELOPMENT
WORK"). The ADDITIONAL DEVELOPMENT WORK shall be conducted under the terms and
conditions of the Agreement, with the following modifications:

     1.   SIEGFRIED shall use commercially diligent efforts to undertake the
          ADDITIONAL DEVELOPMENT WORK with the goal of completing the work
          within [**] of initiation of the work.

     2.   MOMENTA shall pay SIEGFRIED a total fee of Two Hundred Thousand
          U.S. Dollars ($200,000) for the ADDITIONAL DEVELOPMENT WORK. Fifty
          percent (50%) of such fee shall be due and payable upon initiation
          of the work and the remaining Fifty percent (50%) shall be due and
          payable upon the issuance of a final development report by SIEGFRIED
          which is reasonably satisfactory to MOMENTA. Invoicing and payment
          shall be in accordance with Section 10.1 of the Agreement. For
          purposes of Section 9.4 of the Agreement, the foregoing fee shall be
          attributed to the ADDITIONAL DEVELOPMENT WORK.

     3.   MOMENTA shall be responsible for supplying the necessary quantities of
          heparin for the ADDITIONAL DEVELOPMENT WORK in accordance with Section
          3.2 of the Agreement.

<Page>

     4.   At the conclusion of the ADDITIONAL DEVELOPMENT WORK, or earlier if
          the parties so agree, the parties shall agree upon the production of
          ENOXAPARIN and/or PRODUCT to be undertaken by SIEGFRIED under the
          Agreement.

If the foregoing is in conformity with your understanding, please execute both
copies of this Letter Agreement and return one fully-executed copy to me.

                             Very truly yours,


                             /s/ JOSEPH E. TYLER
                              Joseph E. Tyler

Agreed and accepted:


SIEGFRIED (USA), INC.

By:  /s/ SCOTT POWERS    Feb. 18, 2004
   ----------------------------------------

SIEGFRIED LTD.

By:  /s/ DENNIS P. BAUER
   ------------------------------------------------

<Page>

                                   APPENDIX A

                                      [**]
                         WORK AT SIEGFRIEDM-ENOX PROJECT


STEP 1
[**]

   [**]
   [**]
   [**]
   Maintain [**]
   Maintain [**]
   [**]
   Will use[**]
   [**]
   [**]

STEP 2
[**]
      [**]
      [**]
      [**]
      [**]
      Will use [**]
      [**]
      [**]
      [**]
[**]
      [**]
      [**]

<Page>

[**]
      [**]
      [**]
      [**]
      [**]
      [**]
      [**]
      [**]
[**]
      [**]
      [**]

STEP 3

[**]
      [**]
      Use [**]
      [**]
      Current [**]
      Add [**]
      [**]
          Add [**]
          Complete [**]
          Start [**]
      [**]
[**]
      [**]
      [**]
      [**]
      [**]
      [**]

<Page>

Momenta Pharmaceuticals, Inc.
43 Moulton Street
Cambridge, Massachusetts 02138

May 17, 2004

Dennis P. Bauer, Ph.D.
Siegfried (USA), Inc.
33 Industrial Park Road
Pennsville, NJ 08070

Dear Dennis:

Reference is made to the Development and Production Agreement for Active
Pharmaceutical Ingredient between Siegfried (USA), Inc. and Siegfried Ltd.
("SIEGFRIED") and Momenta Pharmaceuticals, Inc. ("MOMENTA") dated October 10,
2003, as amended by Letter Agreement dated February 14, 2004 (the "Agreement").
Capitalized terms used herein and not otherwise defined shall have the meanings
given such terms in the Agreement.

MOMENTA hereby engages SIEGFRIED to undertake certain additional production work
which work is known as the second campaign by MOMENTA and SIEGFRIED (the
"ADDITIONAL PRODUCTION WORK"). The ADDITIONAL PRODUCTION WORK shall be conducted
under the terms and conditions of the Agreement, with the following
modifications:

1. Each BATCH of PRODUCT manufactured as part of the ADDITIONAL PRODUCTION WORK
shall be manufactured in accordance with the then-current SPECIFICATIONS.

2. SIEGFRIED shall use commercially diligent efforts to undertake the ADDITIONAL
PRODUCTION WORK, with the goal of completing each BATCH within the estimated
time frame for each such BATCH.

3. MOMENTA shall pay SIEGFRIED a fee of Two Hundred Twenty Thousand U.S. Dollars
($220,000) per authorized BATCH, for a total fee of up to One Million One
Hundred Thousand U.S. Dollars ($1,100,000) for the ADDITIONAL PRODUCTION WORK.
The fee for each BATCH shall be payable upon the delivery to MOMENTA of such
BATCH. The foregoing fees shall be exclusive of amounts due for specialized
equipment rental and amounts due PPD Development LP for the analytical testing
to be conducted by PPD Development LP. Invoicing and payment shall be in
accordance with Section 10.1 of the Agreement. For purposes of Section 9.4 of
the Agreement, the foregoing fees shall be attributable to the ADDITIONAL
PRODUCTION WORK and Actual Cost shall be determined in accordance with the first
sentence thereof.

4. MOMENTA shall be responsible for supplying the necessary quantities of
heparin for the ADDITIONAL PRODUCTION WORK in accordance with Section 3.2 of the
Agreement. MOMENTA hereby engages SIEGFRIED to undertake certain further
development work as is mutually agreed to by MOMENTA and SIEGFRIED in writing
(the "FURTHER

<PAGE>


DEVELOPMENT WORK"). The FURTHER DEVELOPMENT WORK shall be conducted under the
terms and conditions of the Agreement, with the following modifications:

5. SIEGFRIED shall use commercially diligent efforts to undertake the FURTHER
DEVELOPMENT WORK.

6. MOMENTA shall pay SIEGFRIED on a time and materials basis for work authorized
by MOMENTA, estimated to total a maximum of Four Hundred Thousand U.S. Dollars
($400,000). For purposes of Section 9.4 of the Agreement, SIEGFRIED shall be
entitled to the Actual Cost of the FURTHER DEVELOPMENT WORK as determined in
accordance with the first sentence thereof.

7. MOMENTA shall be responsible for supplying the necessary quantities of
heparin for the FURTHER DEVELOPMENT WORK in accordance with Section 3.2 of the
Agreement. MOMENTA and SIEGFRIED acknowledge that it is MOMENTA's intent to
file, directly or through a designee, an Abbreviated New Drug Application
("ANDA") covering the PRODUCT with the FDA. In connection therewith, MOMENTA and
SIEGFRIED hereby agree that the Agreement shall be amended as follows:

8. As part of its general obligations under the Agreement, SIEGFRIED agrees to
provide reasonable assistance to MOMENTA, or MOMENTA's designee, in connection
with MOMENTA's, or MOMENTA's designee's, submission of the ANDA covering the
PRODUCT with the FDA and in connection with the corresponding regulatory review
process undertaken by the FDA including, without limitation, (a) assistance with
the compilation of the dossier for the ANDA, (b) allowance of, and participation
in, any required pre-approval inspections by the FDA in connection with the
ANDA, and (c) assistance in responding to any inquiries of, or deficiency
letters sent by, the FDA during the process for approval of the ANDA. Further,
this provision shall be added to the provisions listed in Section 9.5 of the
Agreement.

MOMENTA hereby engages SIEGFRIED to undertake the validation of certain
analytical methods as are mutually agreed upon by MOMENTA and SIEGFRIED in
writing ("METHOD VALIDATION"). The METHOD VALIDATION shall be conducted under
the terms and conditions of the Agreement, with the following modifications:

9. SIEGFRIED shall use commercially diligent efforts to undertake the METHOD
VALIDATION with the goal of completing the work within the estimated time frame
for such work.

10. MOMENTA shall pay SIEGFRIED a total fee of Sixty Five Thousand U.S. Dollars
($65,000.00) for the METHOD VALIDATION. Fifty percent (50%) of such fee shall be
due and payable upon initiation of the work and the remaining fifty percent
(50%) shall be due and payable upon the receipt by MOMENTA of the validation
protocol, final analytical method and final validation report of SIEGFRIED, all
of which shall be reasonably satisfactory to MOMENTA. Invoicing and payment
shall be in accordance with Section 10.1 of the Agreement. For purposes of
Section 9.4 of the Agreement, the foregoing fee shall be attributed to the
METHOD VALIDATION and Actual Cost shall be determined in accordance with the
first sentence thereof.

<PAGE>


If the foregoing is in conformity with your understanding, please execute both
copies of this Letter Agreement and return one fully-executed copy to me.

                                   Very truly yours,

                                   /s/ Steven B. Brugger
                                   Steven B. Brugger
                                   Vice President, Strategic Product Development
Agreed and accepted:

SIEGFRIED (USA), INC.

By: /s/ DONALD O. BELL    May 19, 2004
    -------------------

SIEGFRIED LTD.

By: /s/ DENNIS P. BAUER
    -------------------