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                                                                   EXHIBIT 10.23

                           LOAN AND SECURITY AGREEMENT

       This LOAN AND SECURITY AGREEMENT (this "Agreement") dated as of December
27, 2002, between SILICON VALLEY BANK, a California chartered bank, with its
principal place of business at 3003 Tasman Drive, Santa Clara, California 95054
and with a loan production office located at One Newton Executive Park, Suite
200, 2221 Washington Street, Newton, Massachusetts 02462, doing business under
the name "Silicon Valley East" ("Bank") and MOMENTA PHARMACEUTICALS, INC., a
Delaware corporation ("Borrower"), provides the terms on which Bank shall lend
to Borrower and Borrower shall repay Bank. The parties agree as follows:

       1      ACCOUNTING AND OTHER TERMS

       Accounting terms not defined in this Agreement shall be construed
following GAAP. Calculations and determinations must be made following GAAP. The
term "financial statements" includes the notes and schedules. The terms
"including" and "includes" always mean "including (or includes) without
limitation," in this or any Loan Document. Capitalized terms in this Agreement
shall have the meanings set forth in Section 13.

       2      LOAN AND TERMS OF PAYMENT

       2.1    PROMISE TO PAY. Borrower hereby unconditionally promises to pay
Bank the unpaid principal amount of all Credit Extensions and interest on the
unpaid principal amount of the Credit Extensions as and when due in accordance
with this Agreement.

       2.1.1         VENTURE EQUIPMENT FACILITY.

              (a)    Subject to the terms and conditions of this Agreement, Bank
agrees to lend to Borrower, from time to time prior to the Commitment
Termination Date, equipment advances (each an "Equipment Advance" and
collectively the "Equipment Advances") in an aggregate amount not to exceed the
Equipment Line. When repaid, the Equipment Advances may not be re-borrowed. The
proceeds of the Equipment Advances shall be used solely to reimburse Borrower
for the purchase of Eligible Equipment purchased within ninety (90) days
(determined based upon the applicable invoice date of such Eligible Equipment)
of the Equipment Advance and to purchase new Eligible Equipment. Bank's
obligation to lend hereunder shall terminate on the earlier of (i) the
occurrence and continuance of an Event of Default, or (ii) the Commitment
Termination Date. For purposes of this Section, the minimum amount of each
Equipment Advance is Fifty Thousand Dollars ($50,000.00). Notwithstanding the
foregoing, the initial Equipment Advance hereunder may be used to reimburse
Borrower for Eligible Equipment purchased on or after June 1, 2002 (the "Initial
Advance"). The Borrower may only request an aggregate of six (6) Equipment
Advances for the financing of Equipment

              (b)    To obtain an Equipment Advance, Borrower shall deliver to
Bank a completed supplement in substantially the form attached as EXHIBIT B
("Loan Supplement"), together with a UCC Financing Statement covering the
Financed Equipment described on Annex

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A to the applicable Loan Supplement and such additional information regarding
the Financed Equipment as Bank may reasonably request at least five (5) Business
Days before the proposed funding date (the "Funding Date"). On each Funding
Date, Bank shall specify in the Loan Supplement for each Equipment Advance, the
Basic Rate, and the Payment Dates. If Borrower satisfies the conditions of each
Equipment Advance, Bank shall disburse such Equipment Advance by internal
transfer to Borrower's deposit account with Bank. Each Equipment Advance may not
exceed 100% of the Original Stated Cost of the Financed Equipment.

       2.1.2  UNDISBURSED CREDIT EXTENSIONS. The Bank's obligation to lend the
undisbursed portion of the Obligations shall terminate if, in Bank's sole
discretion, there has been a material adverse change in the general affairs,
management, results of operation, condition (financial or otherwise) of the
Borrower or the prospect of repayment of the Obligations, or there has been any
material adverse deviation by Borrower from the most recent business plan of
Borrower presented to and accepted by Bank prior to the execution of this
Agreement.

       2.2    INTEREST RATE; PAYMENTS.

              (a)    PRINCIPAL AND INTEREST PAYMENTS ON PAYMENT DATES. Borrower
shall repay each Equipment Advance pursuant to the terms set forth in the
corresponding Loan Supplement. For each Equipment Advance, Borrower shall make
equal monthly payments of principal and interest, in advance, calculated by the
Bank based upon: (1) the amount of the Equipment Advance, (2) the Basic Rate,
and (3) an amortization schedule equal to the Repayment Period (individually,
the "Scheduled Payment", and collectively, "Scheduled Payments"), on the first
Business Day of the month following the month in which the Funding Date occurs
(or commencing on the Funding Date if the Funding Date is the first Business Day
of the month) with respect to such Equipment Advance and continuing thereafter
during the Repayment Period on the first Business Day of each successive
calendar month (each a "Payment Date"). All unpaid principal and accrued
interest is due and payable in full on the last Payment Date with respect to
such Equipment Advance. Payments received after 12:00 noon Eastern time are
considered received at the opening of business on the next Business Day. An
Equipment Advance may only be prepaid in accordance with Sections 2.2(e),
2.2(f), and 2.2(g).

              (b)    INTEREST RATE. Borrower shall pay interest on each Payment
Date on the unpaid principal amount of each Equipment Advance until the
Equipment Advance has been paid in full, fixed at the per annum rate of interest
equal to the Basic Rate determined by Bank as of the Funding Date for each
Equipment Advance in accordance with the definition of the Basic Rate. Any
amounts outstanding during the continuance of an Event of Default shall bear
interest at a per annum rate equal to the Basic Rate plus five percent (5%)(the
"Default Rate").

              (c)    INTERIM PAYMENT. In addition to the Scheduled Payments, on
the Funding Date for each Equipment Advance (unless the Funding Date is the
first Business Day of the month) Borrower shall pay to the Bank, an amount (the
"Interim Payment") equal to (i) the subject Equipment Advance multiplied by (ii)
the sum of the Prime Rate plus Two Percent (2%), divided by (iii) 360 days and
then multiplied by (iv) the number of days from the actual Funding Date of the
Equipment Advance until the first day of the month following such Equipment
Advance.

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              (d)    FINAL PAYMENT. On the Maturity Date with respect to each
Equipment Advance, Borrower shall pay, in addition to the unpaid principal and
accrued interest and all other amounts due on such date with respect to such
Equipment Advance, an amount equal to the Final Payment.

              (e)    PREPAYMENT UPON AN EVENT OF LOSS. If any Financed Equipment
is subject to an Event of Loss and Borrower is required to or elects to prepay
the Equipment Advance with respect to such Financed Equipment pursuant to
Section 6.8, then such Equipment Advance shall be prepaid to the extent and in
the manner provided in such section.

              (f)    MANDATORY PREPAYMENT UPON AN ACCELERATION. If the Equipment
Advances are accelerated following the occurrence of an Event of Default or
otherwise, Borrower shall immediately pay to Bank an amount equal to the sum of
(i) all outstanding principal plus accrued interest, (ii) the Final Payment plus
(iii) all other sums, if any, that shall have become due and payable, including
interest at the Default Rate with respect to any past due amounts.

              (g)    PERMITTED PREPAYMENT OF LOANS. Borrower shall have the
option to prepay any or all of the Equipment Advances advanced by Bank under
this Agreement, PROVIDED Borrower (i) provides written notice to Bank of its
election to prepay any Equipment Advance or all Equipment Advances at least ten
(10) days prior to such prepayment, and (ii) pays, on the date of such
prepayment (A) all outstanding principal plus accrued interest with respect to
such Equipment Advance, (B) the Final Payment with respect to such Equipment
Advance plus (C) all other sums, if any, that shall have become due and payable,
including interest at the Default Rate with respect to any past due amounts,
with respect to such Equipment Advance.

              (h)    DEBIT OF ACCOUNTS. Bank may debit any of Borrower's
deposit accounts including Account Number __________ for principal and
interest payments or any amounts Borrower owes Bank. Bank shall promptly
notify Borrower when it debits Borrower's accounts. These debits are not a
set-off.

       2.3    FEES. Borrower shall pay to Bank:

              (a)    FINAL PAYMENT. The Final Payment, when due hereunder; and

              (b)    BANK EXPENSES. All Bank Expenses (including reasonable
attorneys' fees and expenses incurred through and after the Closing Date) when
due.

       2.4    ADDITIONAL COSTS. If any new law or regulation increases Bank's
costs or reduces its income for any loan, Borrower shall pay the increase in
cost or reduction in income or additional expense; PROVIDED, HOWEVER, that
Borrower shall not be liable for any amount attributable to any period before
180 days prior to the date Bank notifies Borrower of such increased costs. Bank
agrees that it shall allocate any increased costs among its customers similarly
affected in good faith and in a manner consistent with Bank's customary
practice.

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       3      CONDITIONS OF LOANS

       3.1    CONDITIONS PRECEDENT TO INITIAL CREDIT EXTENSION. The Bank's
obligation to make the initial Credit Extension is subject to the condition
precedent that Bank shall have received, in form and substance satisfactory to
Bank, the following:

              (a)    this Agreement;

              (b)    a certificate of the Secretary of Borrower with respect to
articles, bylaws, incumbency and resolutions authorizing the execution and
delivery of this Agreement;

              (c)    Negative Pledge Agreement covering Intellectual Property;

              (d)    landlord's waiver (from sub-lessor);

              (e)    a legal opinion of Borrower's counsel, in form and
substance acceptable to Bank;

              (f)    Warrant to Purchase Stock;

              (g)    financing statements (Forms UCC-1);

              (h)    Account Control Agreement/ Investment Account Control
Agreement;

              (i)    insurance certificate;

              (j)    payment of the fees and Bank Expenses then due specified in
Section 2.4 hereof;

              (k)    Certificate of Foreign Qualification (Massachusetts);

              (l)    Certificate of Good Standing/Legal Existence (Delaware);
and

              (m)    such other documents, and completion of such other matters,
as Bank may reasonably deem necessary or appropriate.

       3.2    CONDITIONS PRECEDENT TO ALL CREDIT EXTENSIONS. Bank's obligations
to make each Credit Extension, including the initial Credit Extension, is
subject to the following:

              (a)    timely receipt of a completed Loan Supplement and UCC
financing statement covering the Financed Equipment described on Annex A to the
Loan Supplement; and

              (b)    the representations and warranties in Section 5 must be
materially true on the date of the Loan Supplement and on the effective date of
each Credit Extension and no Event of Default shall have occurred and be
continuing as of such effective date, or result from the Credit Extension. Each
delivery of a completed Loan Supplement to Bank is Borrower's representation and
warranty on that date that the representations and warranties in Section 5
remain materially true on the date thereof.

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       4      CREATION OF SECURITY INTEREST

       4.1    GRANT OF SECURITY INTEREST. Borrower hereby grants Bank, to secure
the payment and performance in full of all of the Obligations and the
performance of each of Borrower's duties under the Loan Documents, a continuing
security interest in, and pledges to the Bank, the Collateral, wherever located,
whether now owned or hereafter acquired or arising, and all proceeds and
products thereof. Borrower warrants and represents that the security interest
granted herein shall be a first priority security interest in the Collateral.
After the occurrence of an Event of Default, Bank may place a "hold" on any
deposit account pledged as Collateral.

       Except as noted on the Perfection Certificate, Borrower is not a party
to, nor is bound by, any license or other agreement with respect to which the
Borrower is the licensee that prohibits or otherwise restricts Borrower from
granting a security interest in Borrower's interest in such license or agreement
or any other property. Without prior consent from Bank, Borrower shall not enter
into, or become bound by, any such license or agreement which is reasonably
likely to have a material impact on Borrower's business or financial condition.
Borrower shall take such steps as Bank reasonably requests to obtain the consent
of, or waiver by, any person whose consent or waiver is necessary for all such
licenses or contract rights to be deemed "Collateral" and for Bank to have a
security interest in those rights where the inclusion of such rights as
"Collateral" or where the ability of the Bank to have a security interest in
such rights might otherwise be restricted or prohibited by the terms of any such
license or agreement, whether now existing or entered into in the future.

       Borrower agrees that any disposition of the Collateral in violation of
this Agreement, by either the Borrower or any other Person, shall be deemed to
violate the rights of the Bank under the Code. If the Agreement is terminated,
Bank's lien and security interest in the Collateral shall continue until
Borrower fully satisfies its Obligations. If Borrower shall at any time, acquire
a commercial tort claim, as defined in the Code, Borrower shall promptly notify
Bank in a writing signed by Borrower of the brief details thereof and grant to
Bank in such writing a security interest therein and in the proceeds thereof,
all upon the terms of this Agreement, with such writing to be in form and
substance satisfactory to Bank.

       4.2    AUTHORIZATION TO FILE FINANCING STATEMENTS. Borrower hereby
authorizes Bank to file financing statements, without notice to Borrower, with
all appropriate jurisdictions in order to perfect or protect Bank's interest or
rights hereunder.

       5      REPRESENTATIONS AND WARRANTIES

       Borrower represents and warrants as follows:

       5.1    DUE ORGANIZATION AND AUTHORIZATION. Borrower and each Subsidiary
is duly existing and in good standing in its state of formation and qualified
and licensed to do business in, and in good standing in, any state in which the
conduct of its business or its ownership of property requires that it be
qualified except where the failure to do so could not reasonably be expected to
cause a Material Adverse Change. In connection with this Agreement, the Borrower
delivered to the Bank a certificate signed by the Borrower and entitled
"Perfection Certificate". The Borrower represents and warrants to the Bank that:
(a) the Borrower's exact legal name is

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that indicated on the Perfection Certificate and on the signature page hereof;
and (b) the Borrower is an organization of the type, and is organized in the
jurisdiction, set forth in the Perfection Certificate; and (c) the Perfection
Certificate accurately sets forth the Borrower's organizational identification
number; and (d) the Perfection Certificate accurately sets forth the Borrower's
place of business, and (e) all other information set forth on the Perfection
Certificate pertaining to the Borrower is accurate and complete. If the Borrower
does not now have an organizational identification number, but later obtains
one, Borrower shall forthwith notify the Bank of such organizational
identification number.

       The execution, delivery and performance of the Loan Documents have been
duly authorized, and do not conflict with Borrower's organizational documents,
nor constitute an event of default under any material agreement by of the
Borrower which Borrower is bound which material agreements are set forth in
SCHEDULE 5.1 attached hereto. Borrower is not in default under any agreement to
which or by which it is bound in which the default could reasonably be expected
to cause a Material Adverse Change.

       5.2    COLLATERAL. Borrower owns the Collateral, free of Liens except
Permitted Liens. Borrower has no deposit account, other than the deposit
accounts with Bank and deposit accounts described in the Perfection Certificate
delivered to the Bank in connection herewith. To the extent existing, the
Accounts are bona fide, obligations, and the service or property has been
performed or delivered to the account debtor or its agent for immediate shipment
to and unconditional acceptance by the account debtor. The Collateral is not in
the possession of any third party bailee (such as a warehouse). In the event
that Borrower, after the date hereof, intends to store or otherwise deliver any
portion of the Collateral to a bailee, then Borrower will first receive the
written consent of Bank and such bailee must acknowledge in writing that the
bailee is holding such Collateral for the benefit of Bank. All Inventory is in
all material respects of good and marketable quality, free from material
defects. Borrower is the sole owner of the Intellectual Property, except for
non-exclusive licenses granted to its customers in the ordinary course of
business. Each Patent is valid and enforceable and no part of the Intellectual
Property has been judged invalid or unenforceable, in whole or in part, and no
claim has been made that any part of the Intellectual Property violates the
rights of any third party except to the extent such claim could not reasonably
be expected to cause a Material Adverse Change.

       5.3    LITIGATION. Except as shown in the Perfection Certificate, there
are no actions or proceedings pending or, to the knowledge of Borrower's
Responsible Officers, threatened by or against Borrower or any Subsidiary in
which an adverse decision could reasonably be expected to cause a Material
Adverse Change.

       5.4    NO MATERIAL DEVIATION IN FINANCIAL STATEMENTS. All consolidated
financial statements for Borrower and any Subsidiary delivered to Bank fairly
present in all material respects Borrower's consolidated financial condition and
Borrower's consolidated results of operations as of the date of such statements.
There has not been any material deterioration in Borrower's consolidated
financial condition since the date of the most recent financial statements of
Borrower delivered by Borrower to Bank.

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       5.5    SOLVENCY. The fair salable value of Borrower's assets (including
goodwill minus disposition costs) exceeds the fair value of its liabilities; the
Borrower is not left with unreasonably small capital after the transactions in
this Agreement; and Borrower is able to pay its debts (including trade debts) as
they mature.

       5.6    REGULATORY COMPLIANCE. Borrower is not an "investment company" or
a company "controlled" by an "investment company" under the Investment Company
Act. Borrower is not engaged as one of its important activities in extending
credit for margin stock (under Regulations T and U of the Federal Reserve Board
of Governors). Borrower has complied in all material respects with the Federal
Fair Labor Standards Act. Borrower has not violated any laws, ordinances or
rules, the violation of which could reasonably be expected to cause a Material
Adverse Change. None of Borrower's or any Subsidiary's properties or assets has
been used by Borrower or any Subsidiary or, to the best of Borrower's knowledge,
by previous Persons, in disposing, producing, storing, treating, or transporting
any hazardous substance other than legally, except where such use could not be
reasonably expected to cause a Material Adverse Change. Borrower and each
Subsidiary has timely filed all required tax returns and paid, or made adequate
provision to pay, all material taxes, except those being contested in good faith
with adequate reserves under GAAP. Borrower and each Subsidiary has obtained all
consents, approvals and authorizations of, made all declarations or filings
with, and given all notices to, all government authorities that are necessary to
continue its business as currently conducted except where the failure to make
such declarations, notices or filings would not reasonably be expected to cause
a Material Adverse Change.

       5.7    SUBSIDIARIES. Borrower does not own any stock, partnership
interest or other equity securities except for Permitted Investments.

       5.8    FULL DISCLOSURE. No written representation, warranty or other
statement of Borrower in any certificate or written statement given to Bank
taken together with all such written certificates and written statements given
to Bank contains any untrue statement of a material fact or omits to state a
material fact necessary to make the statements contained in the certificates or
statements not misleading (it being recognized by Bank that the projections and
forecasts provided by Borrower in good faith and based upon reasonable
assumptions are not viewed as facts and that actual results during the period or
periods covered by such projections and forecasts may differ from the projected
or forecasted results).

       6      AFFIRMATIVE COVENANTS

       Borrower shall do all of the following:

       6.1    GOVERNMENT COMPLIANCE. Borrower shall maintain its and all
Subsidiaries' legal existence and good standing in its jurisdiction of formation
and maintain qualification in each jurisdiction in which the failure to so
qualify would reasonably be expected to cause a Material Adverse Change.
Borrower shall comply, and have each Subsidiary comply, with all laws,
ordinances and regulations to which it is subject, where noncompliance with such
laws, ordinance and regulations could have a material adverse effect on
Borrower's business or operations or would reasonably be expected to cause a
Material Adverse Change.

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       6.2    FINANCIAL STATEMENTS, REPORTS, CERTIFICATES.

              (a)    Borrower shall deliver to Bank: (i) as soon as available,
but no later than thirty (30) days after the last day of each month, a
company-prepared consolidated balance sheet and income statement covering
Borrower's consolidated operations during the period certified by a Responsible
Officer and in a form acceptable to Bank; (ii) as soon as available, but no
Later than one hundred and twenty (120) days after the last day of Borrower's
fiscal year, audited consolidated financial statements prepared under GAAP,
consistently applied, together with an unqualified opinion on the financial
statements from an independent certified public accounting firm reasonably
acceptable to Bank; (iii) in the event that the Borrower's stock becomes
publicly held, within five (5) days of filing, copies of all statements, reports
and notices made available to Borrower's security holders or to any holders of
Subordinated Debt and all reports on Form 10-K, 10-Q and 8-K filed with the
Securities and Exchange Commission; (iv) a prompt report of any legal actions
pending or threatened against Borrower or any Subsidiary that could reasonably
be expected to result in damages or costs to Borrower or any Subsidiary of Two
Hundred Fifty Thousand Dollars ($250,000.00) or more; and (vi) other financial
information reasonably requested by Bank.

              (b)    Borrower shall also deliver to Bank with the monthly and
annual financial statements a Compliance Certificate signed by a Responsible
Officer in the form of EXHIBIT C.

       6.3    INVENTORY; RETURNS. Borrower shall keep all Inventory in good and
marketable condition, free from material defects. Returns and allowances between
Borrower and its account debtors shall follow Borrower's customary practices as
they exist at the Closing Date. Borrower must promptly notify Bank of all
returns, recoveries, disputes and claims that involve more than Fifty Thousand
Dollars ($50,000.00).

       6.4    TAXES. Borrower shall make, and cause each Subsidiary to make,
timely payment of all material federal, state, and local taxes or assessments
(other than taxes and assessments which Borrower is contesting in good faith,
with adequate reserves maintained in accordance with GAAP) and will deliver to
Bank, on demand, appropriate certificates attesting to such payments.

       6.5    INSURANCE. Borrower shall keep its business and the Collateral
insured for risks in amounts as Bank may reasonably request. Insurance policies
shall be in a form with companies, and in amounts that are satisfactory to Bank.
All property policies shall have a lender's loss payable endorsement showing
Bank as an additional loss payee, all liability policies shall show the Bank as
an additional insured and all policies shall provide that the insurer must give
Bank at least twenty (20) days notice before canceling its policy. At Bank's
request, Borrower shall deliver certified copies of policies and evidence of all
premium payments. Proceeds payable under any policy shall, at Bank's option, be
payable to Bank on account of the Obligations. Notwithstanding the foregoing, so
long as no Event of Default has occurred and is continuing, Borrower shall have
the option of applying the proceeds of any casualty policy up to $100,000.00, in
the aggregate, toward the replacement or repair of destroyed or damaged
property; provided that (i) any such replaced or repaired property (a) shall be
of equal or like value as the replaced or repaired property and (b) shall be
deemed Collateral in which Bank has

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been granted a first priority security interest and (ii) after the occurrence
and during the continuation of an Event of Default all proceeds payable under
such casualty policy shall, at the option of the Bank, be payable to Bank on
account of the Obligations. If Borrower fails to obtain insurance as required
under this Section 6.5 or to pay any amount or furnish any required proof of
payment to third persons and the Bank, Bank may make all or part of such payment
or obtain such insurance policies required in this Section 6.5, and take any
reasonable action under the policies Bank deems prudent.

       6.6    ACCOUNTS.

              (a)    In order to permit the Bank to monitor the Borrower's
financial performance and condition, Borrower, and all Borrower's Subsidiaries,
shall maintain Borrower's primary depository, operating, and securities accounts
with Bank and a portion of the Borrower's excess cash or securities in excess of
that amount used for Borrower's operations shall be maintained or administered
through the Bank.

              (b)    Borrower shall identify to Bank, in writing, any bank or
securities account opened by Borrower with any institution other than Bank. In
addition, for each such account that the Borrower at any time opens or
maintains, Borrower shall, at the Bank's request and option, pursuant to an
agreement in form and substance acceptable to the Bank, cause the depositary
bank or securities intermediary to agree that such account is the collateral of
the Bank pursuant to the terms hereunder. The provisions of the previous
sentence shall not apply to: (i) deposit accounts exclusively used for payroll,
payroll taxes and other employee wage and benefit payments to or for the benefit
of the Borrower's employees, or (ii) accounts at other institutions provided
that the Borrower maintains at least One Million Dollars ($1,000,000.00) in
unrestricted funds at the Bank, at all times.

       6.7    FURTHER ASSURANCES. Borrower shall execute any further instruments
and take further action as Bank reasonably requests to perfect or continue
Bank's security interest in the Collateral or to effect the purposes of this
Agreement.

       6.8    LOSS; DESTRUCTION; OR DAMAGE. Borrower shall bear the risk of the
Financed Equipment being lost, stolen, destroyed, or damaged. If during the term
of this Agreement any item of Financed Equipment becomes obsolete or is lost,
stolen, destroyed, damaged beyond repair, rendered permanently unfit for use, or
seized by a governmental authority for any reason for a period equal to at least
the remainder of the term of this Agreement (an "Event of Loss"), then in each
case, Borrower:

              (a)    prior to the occurrence of an Event of Default, at
Borrower's option, shall (i) pay to Bank on account of the Obligations all
accrued interest to the date of the prepayment, plus all outstanding principal,
plus the Final Payment with respect to the Financed Equipment that suffered an
Event of Loss; or (ii) repair or replace any such Financed Equipment subject to
an Event of Loss provided the repaired or replaced Financed Equipment is of
equal or like value to the Financed Equipment subject to an Event of Loss and
provided further that Bank obtains a first priority perfected security interest
in such repaired or replaced Financed Equipment.

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              (b)    during the continuance of an Event of Default, on or before
the next Payment Date following such Event of Loss, for each such item of
Financed Equipment subject to such Event of Loss, Borrower shall, at Bank's
option, pay to Bank an amount equal to the sum of the following with respect to
the Financed Equipment subject to the Event of Loss: (i) all outstanding
principal plus accrued interest, (ii) the Final Payment plus (iii) all other
sums, if any, that shall have become due and payable, including interest at the
Default Rate with respect to any past due amounts.

       7      NEGATIVE COVENANTS

       Borrower shall not do any of the following without the Bank's prior
written consent which shall not be unreasonably withheld.

       7.1    DISPOSITIONS. Convey, sell, lease, transfer or otherwise dispose
of (collectively a "Transfer"), or permit any of its Subsidiaries to Transfer,
all or any part of its business or property, except for Transfers (i) of
Inventory in the ordinary course of business; (ii) of licenses and similar
arrangements for the use of the property of Borrower or its Subsidiaries in the
ordinary course of business and licenses granted in connection with the
consummation of collaborations, joint ventures, or financing arrangements with
the Borrower's business partners in the ordinary course of business; or (iii) of
worn-out or obsolete Collateral.

       7.2    CHANGES IN BUSINESS, OWNERSHIP, MANAGEMENT OR BUSINESS LOCATIONS.
Engage in or permit any of its Subsidiaries to engage in any business other than
the businesses currently engaged in by Borrower or reasonably related thereto,
or have a material change in its ownership (other than by the sale of Borrower's
equity securities in a public offering or to venture capital investors so long
as Borrower identifies to Bank the venture capital investors prior to the
closing of the investment), or management. Borrower shall not, without at least
thirty (30) days prior written notice to Bank: (i) relocate its chief executive
office, or add any new offices or business locations, including warehouses
(unless such new offices or business locations contain less than Fifty Thousand
Dollars ($50,000.00) in Borrower's assets or property), or (ii) change its
jurisdiction of organization, or (iii) change its organizational structure or
type, or (iv) change its legal name, or (v) change any organizational number (if
any) assigned by its jurisdiction of organization.

       7.3    MERGERS OR ACQUISITIONS. Merge or consolidate, or permit any of
its Subsidiaries to merge or consolidate, with any other Person, or acquire, or
permit any of its Subsidiaries to acquire, all or substantially all of the
capital stock or property of another Person. Notwithstanding the foregoing, a
Subsidiary may merge or consolidate into another Subsidiary or into Borrower.

       7.4    INDEBTEDNESS. Create, incur, assume, or be liable for any
Indebtedness, or permit any Subsidiary to do so, other than Permitted
Indebtedness.

       7.5    ENCUMBRANCE. Create, incur, or allow any Lien on any of its
property, or assign or convey any right to receive income, including the sale of
any Accounts, or permit any of its Subsidiaries to do so, except for Permitted
Liens, or permit any Collateral not to be subject to the

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first priority security interest granted herein. Notwithstanding the foregoing,
the Collateral may also be subject to Permitted Liens.

       7.6    DISTRIBUTIONS; INVESTMENTS. (i) Directly or indirectly acquire or
own any Person, or make any Investment in any Person, other than Permitted
Investments, or permit any of its Subsidiaries to do so; or (ii) pay any
dividends or make any distribution or payment or redeem, retire or purchase any
capital stock.

       7.7    TRANSACTIONS WITH AFFILIATES. Directly or indirectly enter into or
permit to exist any material transaction with any Affiliate of Borrower, except
for transactions that are in the ordinary course of Borrower's business, upon
fair and reasonable terms that are no less favorable to Borrower than would be
obtained in an arm's length transaction with a non-affiliated Person.

       7.8    SUBORDINATED DEBT. Make or permit any payment on any Subordinated
Debt, except under the terms of the Subordinated Debt, or amend any material
provision in any document relating to the Subordinated Debt, without Bank's
prior written consent.

       7.9    COMPLIANCE. Become an "investment company" or a company controlled
by an "investment company", under the Investment Company Act of 1940 or
undertake as one of its important activities extending credit to purchase or
carry margin stock, or use the proceeds of any Credit Extension for that
purpose; fail to meet the minimum funding requirements of ERISA, permit a
Reportable Event or Prohibited Transaction, as defined in ERISA, to occur; fail
to comply with the Federal Fair Labor Standards Act or violate any other law or
regulation, if the violation could reasonably be expected to cause a Material
Adverse Change.

       8      EVENTS OF DEFAULT

       Any one of the following is an Event of Default:

       8.1    PAYMENT DEFAULT. Borrower fails to pay any of the Obligations
within three (3) Business Days after their due date. During the additional
period the failure to cure the default is not an Event of Default (but no Credit
Extension shall be made during the cure period);

       8.2    COVENANT DEFAULT. Borrower fails or neglects to perform any
obligation in Section 6 or violates any covenant in Section 7 or fails or
neglects to perform, keep, or observe any other material term, provision,
condition, covenant or agreement contained in this Agreement, any Loan
Documents, or in any present or future agreement between Borrower and Bank and
as to any default under such other material term, provision, condition, covenant
or agreement that can be cured, has failed to cure the default within ten (10)
days after the occurrence thereof; provided, however, that if the default cannot
by its nature be cured within the ten (10) day period or cannot after diligent
attempts by Borrower be cured within such ten (10) day period, and such default
is likely to be cured within a reasonable time, then Borrower shall have an
additional period (which shall not in any case exceed thirty (30) days) to
attempt to cure such default, and within such reasonable time period the failure
to cure the default shall not be deemed an Event of Default (but no Credit
Extensions shall be made during such cure period). Grace periods provided under
this section shall not apply to financial covenants or any other covenants that
are required to be satisfied, completed or tested by a date certain.

                                       11
<Page>

       8.3    MATERIAL ADVERSE CHANGE. A Material Adverse Change occurs;

       8.4    ATTACHMENT. (i) Any material portion of Borrower's assets is
attached, seized, levied on, or comes into possession of a trustee or receiver
and the attachment, seizure or levy is not removed in ten (10) days; (ii) the
service of process upon the Borrower seeking to attach, by trustee or similar
process, any funds of the Borrower on deposit with the Bank; (iii) Borrower is
enjoined, restrained, or prevented by court order from conducting a material
part of its business; (iv) a judgment or other claim becomes a Lien on a
material portion of Borrower's assets; or (v) a notice of lien, levy, or
assessment is filed against any of Borrower's assets by any government agency
and not paid within ten (10) days after Borrower receives notice. These are not
Events of Default if stayed or if a bond is posted pending contest by Borrower
(but no Credit Extensions shall be made during the cure, stay, or contest
period);

       8.5    INSOLVENCY. (i) Borrower becomes insolvent; (ii) Borrower begins a
voluntary Insolvency Proceeding; or (iii) an Insolvency Proceeding is begun
against Borrower and not dismissed or stayed within thirty (30) days (but no
Credit Extensions shall be made before any Insolvency Proceeding is dismissed);

       8.6    OTHER AGREEMENTS. If there is a default in any agreement to which
Borrower is a party with a third party or parties resulting in a right by such
third party or parties, whether or not exercised, to accelerate the maturity of
any Indebtedness in an amount in excess of Two Hundred Fifty Thousand Dollars
($250,000) or that could be reasonably expected to result in a Material Adverse
Change;

       8.7    JUDGMENTS. If a judgment or judgments for the payment of money in
an amount, individually or in the aggregate, of at least Two Hundred Fifty
Thousand Dollars ($250,000) shall be rendered against Borrower and shall remain
unsatisfied and unstayed for a period of ten (10) days (provided that no Credit
Extensions will be made prior to the satisfaction or stay of such judgment);

       8.8    MISREPRESENTATIONS. If Borrower or any Person acting for Borrower
makes any material misrepresentation or material misstatement now or later in
any warranty or representation in this Agreement or in any writing delivered to
Bank or to induce Bank to enter this Agreement or any Loan Document.

       9      BANK'S RIGHTS AND REMEDIES

       9.1    RIGHTS AND REMEDIES. When an Event of Default occurs and continues
Bank may, without notice or demand, do any or all of the following:

              (a)    Declare all Obligations immediately due and payable (but if
an Event of Default described in Section 8.5 occurs all Obligations are
immediately due and payable without any action by Bank);

              (b)    Stop advancing money or extending credit for Borrower's
benefit under this Agreement or under any other agreement between Borrower and
Bank;

                                       12
<Page>

              (c)    Settle or adjust disputes and claims directly with account
debtors for amounts, on terms and in any order that Bank considers advisable and
which is commercially reasonable and notify any Person owing Borrower money of
Bank's security interest in such funds and verify the amount of such account.
Borrower shall after notice collect all payments from account debtors in trust
for Bank and, if requested by Bank, immediately deliver the payments to Bank in
the form received from the account debtor, with proper endorsements for deposit;

              (d)    Make any payments and do any acts it considers necessary or
reasonable to protect its security interest in the Collateral. Borrower shall
assemble the Collateral if Bank requests and make it available as Bank
designates. Bank may enter premises where the Collateral is located, take and
maintain possession of any part of the Collateral, and pay, purchase, contest,
or compromise any Lien which , in the reasonable judgment of the Bank, appears
to be prior or superior to its security interest and pay all expenses incurred.
Borrower grants Bank a license to enter and occupy any of its premises, without
charge, to exercise any of Bank's rights or remedies;

              (e)    Apply to the Obligations any (i) balances and deposits of
Borrower it holds, or (ii) any amount held by Bank owing to or for the credit or
the account of Borrower;

              (f)    Ship, reclaim, recover, store, finish, maintain, repair,
prepare for sale, advertise for sale, and sell the Collateral. Bank is hereby
granted a non-exclusive, royalty-free license or other right to use, without
charge, Borrower's labels, patents, copyrights, mask works, rights of use of any
name, trade secrets, trade names, trademarks, service marks, and advertising
matter, or any similar property as it pertains to the Collateral, in completing
production of, advertising for sale, and selling any Collateral except as
prohibited by contract or applicable law and, in connection with Bank's exercise
of its rights under this Section, Borrower's rights under all licenses and all
franchise agreements inure to Bank's benefit except as prohibited by contract or
applicable law;

              (g)    Dispose of the Collateral according to the Code; and

              (h)    Issue a notice of exclusive control under the Securities
Account Control Agreement, of even date herewith.

       9.2    POWER OF ATTORNEY. Borrower hereby irrevocably appoints Bank as
its lawful attorney-in-fact, to be effective upon the occurrence and during the
continuance of an Event of Default and until the Obligations have been satisfied
in full and Bank is under no further obligation to make Credit Extensions
hereunder, to: (i) endorse Borrower's name on any checks or other forms of
payment or security; (ii) sign Borrower's name on any invoice or bill of lading
for any Account or drafts against account debtors; (iii) settle and adjust
disputes and claims about the Accounts directly with account debtors, for
amounts and on terms Bank determines reasonable; (iv) make, settle, and adjust
all claims under Borrower's insurance policies for commercially reasonable
amounts; and (v) transfer the Collateral into the name of Bank or a third party
as the Code permits. Borrower hereby appoints Bank as its lawful
attorney-in-fact to sign Borrower's name on any documents necessary to perfect
or continue the perfection of any security interest regardless of whether an
Event of Default has occurred until all Obligations

                                       13
<Page>

have been satisfied in full and Bank is under no further obligation to make
Credit Extensions hereunder. Bank's foregoing appointment as Borrower's attorney
in fact, and all of Bank's rights and powers, coupled with an interest, are
irrevocable until all Obligations have been fully repaid and performed and
Bank's obligation to provide Credit Extensions terminates.

       9.3    ACCOUNTS NOTIFICATION/COLLECTION. In the event that an Event of
Default occurs and is continuing, Bank may notify any Person owing Borrower
money of Bank's security interest in the funds and verify and/or collect the
amount of the Account. After the occurrence and during the continuance of an
Event of Default and notice to the Borrower, any amounts received by Borrower
shall be held in trust by Borrower for Bank, and, if requested by Bank, Borrower
shall immediately deliver such receipts to Bank in the form received from the
account debtor, with proper endorsements for deposit.

       9.4    BANK EXPENSES. Any amounts owing by Borrower and paid by Bank as
provided herein are Bank Expenses and are immediately due and payable, and shall
bear interest at the then applicable rate and be secured by the Collateral. No
payments by Bank shall be deemed an agreement to make similar payments in the
future or Bank's waiver of any Event of Default.

       9.5    BANK'S LIABILITY FOR COLLATERAL. So long as the Bank complies with
reasonable banking practices regarding the safekeeping of collateral, (i) the
Bank shall not be liable or responsible, except as a result of its gross
negligence or willful misconduct, for: (a) the safekeeping of the Collateral;
(b) any loss or damage to the Collateral; (c) any diminution in the value of the
Collateral; or (d) any act or default of any carrier, warehouseman, bailee, or
other person; and (ii) Borrower bears all risk of loss, damage or destruction of
the Collateral.

       9.6    REMEDIES CUMULATIVE. Bank's rights and remedies under this
Agreement, the Loan Documents, and all other agreements are cumulative. Bank has
all rights and remedies provided under the Code, by law, or in equity. Bank's
exercise of one right or remedy is not an election, and Bank's waiver of any
Event of Default is not a continuing waiver. Bank's delay is not a waiver,
election, or acquiescence. No waiver hereunder shall be effective unless signed
by Bank and then is only effective for the specific instance and purpose for
which it was given.

       9.7    DEMAND WAIVER. Borrower waives (a) demand; (b) notice of default
or dishonor; (c) notice of payment and nonpayment; (d) notice of any default,
nonpayment at maturity, release, compromise, settlement, extension, or renewal
of accounts, documents, instruments, chattel paper, or guarantees held by Bank
on which Borrower is liable.

       10     NOTICES

       All notices or demands by any party to this Agreement or any other
related agreement must be in writing and be personally delivered or sent by an
overnight delivery service, by certified mail, postage prepaid, return receipt
requested, or by telefacsimile at the addresses listed below. Either Bank or
Borrower may change its notice address by giving the other written notice.

       If to Borrower:              Momenta Pharmaceuticals, Inc.
                                    23 Moulton Street

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<Page>

                                    Cambridge, Massachusetts 02138
                                    Attn: Ms.  Susan Whoriskey
                                    FAX: (617) 491-9701

       with a copy to:              Hale and Don LLP
                                    60 State Street
                                    Boston, Massachusetts 02109
                                    Attn.: Steven D.  Singer, Esquire
                                    FAX: (617)526-5000

       If to Bank:                  Silicon Valley Bank
                                    One Newton Executive Park, Suite 200
                                    2221 Washington Street
                                    Newton, Massachusetts 02462
                                    Attn: Mr.  Michael Hanewich
                                    Fax: (617) 969-4395

       with a copy to:              Riemer & Braunstein LLP
                                    Three Center Plaza
                                    Boston, Massachusetts 02108
                                    Attn: David A.  Ephraim, Esquire
                                    FAX: (617) 880-3456

       11     CHOICE OF LAW, VENUE AND JURY TRIAL WAIVER

       Massachusetts law governs the Loan Documents without regard to principles
of conflicts of law. Borrower and Bank each submit to the exclusive jurisdiction
of the State and Federal courts in Massachusetts; provided, however, that if for
any reason Bank cannot avail itself of such courts in the Commonwealth of
Massachusetts, Borrower accepts jurisdiction of the courts and venue in Santa
Clara County, California. NOTWITHSTANDING THE FOREGOING, THE BANK SHALL HAVE THE
RIGHT TO BRING ANY ACTION OR PROCEEDING AGAINST THE BORROWER OR ITS PROPERTY IN
THE COURTS OF ANY OTHER JURISDICTION WHICH THE BANK DEEMS NECESSARY OR
APPROPRIATE IN ORDER TO REALIZE ON THE COLLATERAL OR TO OTHERWISE ENFORCE THE
BANK'S RIGHTS AGAINST THE BORROWER OR ITS PROPERTY.

       BORROWER AND BANK EACH WAIVE THEIR RIGHT TO A JURY TRIAL OF ANY CLAIM OR
CAUSE OF ACTION ARISING OUT OF OR BASED UPON THIS AGREEMENT, THE LOAN DOCUMENTS
OR ANY CONTEMPLATED TRANSACTION, INCLUDING CONTRACT, TORT, BREACH OF DUTY AND
ALL OTHER CLAIMS. THIS WAIVER IS A MATERIAL INDUCEMENT FOR BOTH PARTIES TO ENTER
INTO THIS AGREEMENT. EACH PARTY HAS REVIEWED THIS WAIVER WITH ITS COUNSEL.

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<Page>

       12     GENERAL PROVISIONS

       12.1   SUCCESSORS AND ASSIGNS. This Agreement binds and is for the
benefit of the successors and permitted assigns of each party. Borrower may not
assign this Agreement or any rights or Obligations under it without Bank's prior
written consent which may be granted or withheld in Bank's reasonable
discretion. Bank has the right, without the consent of or notice to Borrower, to
sell, transfer, negotiate, or grant participation in all or any part of, or any
interest in, Bank's obligations, rights and benefits under this Agreement, the
Loan Documents or any related agreement.

       12.2   INDEMNIFICATION. Borrower hereby indemnifies, defends and holds
the Bank and its officers, employees and agents against: (a) all obligations,
demands, claims, and liabilities asserted by any other party in connection with
the transactions contemplated by the Loan Documents; and (b) all losses or Bank
Expenses incurred, or paid by Bank from, following, or consequential to
transactions between Bank and Borrower (including reasonable attorneys' fees and
expenses), except for in the case of (a) and (b) above where such obligations,
demands, claims, liabilities, losses or Bank Expenses are caused by Bank's gross
negligence or willful misconduct.

       12.3   RIGHT OF SET-OFF. Borrower hereby grants to Bank, a lien, security
interest and right of setoff as security for all Obligations to Bank, whether
now existing or hereafter arising upon and against all deposits, credits,
collateral and property, now or hereafter in the possession, custody,
safekeeping or control of Bank or any entity under the control of the Bank or in
transit to any of them. At any time after the occurrence and during the
continuance of an Event of Default, without demand or notice, Bank may set off
the same or any part thereof and apply the same to any of the Obligations. ANY
AND ALL RIGHTS TO REQUIRE BANK TO EXERCISE ITS RIGHTS OR REMEDIES WITH RESPECT
TO ANY OTHER COLLATERAL WHICH SECURES THE OBLIGATIONS, PRIOR TO EXERCISING ITS
RIGHT OF SETOFF WITH RESPECT TO SUCH DEPOSITS, CREDITS OR OTHER PROPERTY OF THE
BORROWER, ARE HEREBY KNOWINGLY, VOLUNTARILY AND IRREVOCABLY WAIVED.

       12.4   TIME OF ESSENCE. Time is of the essence for the performance of all
obligations in this Agreement.

       12.5   SEVERABILITY OF PROVISION. Each provision of this Agreement is
severable from every other provision in determining the enforceability of any
provision.

       12.6   AMENDMENTS IN WRITING; INTEGRATION. All amendments to this
Agreement must be in writing signed by both Bank and Borrower. This Agreement
and the Loan Documents represent the entire agreement about this subject matter,
and supersede prior negotiations or agreements. All prior agreements,
understandings, representations, warranties, and negotiations between the
parties about the subject matter of this Agreement and the Loan Documents merge
into this Agreement and the Loan Documents.

                                       16
<Page>

       12.7   COUNTERPARTS. This Agreement may be executed in any number of
counterparts and by different parties on separate counterparts, each of which,
when executed and delivered, are an original, and all taken together, constitute
one Agreement.

       12.8   SURVIVAL. All covenants, representations and warranties
made in this Agreement continue in full force while any Obligations remain
outstanding. The obligation of Borrower in Section 12.2 to indemnify Bank shall
survive until the statute of limitations with respect to such claim or cause of
action shall have run.

       12.9   CONFIDENTIALITY. In handling any confidential information, Bank
shall exercise the same degree of care that it exercises for its own proprietary
information, but disclosure of information may be made: (i) to Bank's
subsidiaries or affiliates in connection with their business with Borrower,
subject to the limitations contained herein; (ii) to prospective transferees or
purchasers of any interest in the Credit Extensions (provided, however, Bank
shall, prior to such a disclosure, use commercially reasonable efforts in
obtaining such prospective transferee's or purchaser's agreement to the terms of
this provision); (iii) as required by law, regulation, subpoena, or other order,
(iv) as required in connection with Bank's examination or audit; and (v) as Bank
considers appropriate in exercising remedies under this Agreement. Confidential
information does not include information that either. (a) is in the public
domain or in Bank's possession when disclosed to Bank, or becomes part of the
public domain after disclosure to Bank without resulting from disclosure by Bank
and through no fault of Bank; or (b) is first disclosed to Bank by a third
party, if Bank does not know that the third party is prohibited from disclosing
the information.

       13     DEFINITIONS

       13.1   DEFINITIONS. In this Agreement:

       "ACCOUNTS" are all existing and later arising accounts, contract rights,
and other obligations owed Borrower in connection with its sale or lease of
goods (including licensing software and other technology) or provision of
services, all credit insurance, guaranties, other security and all merchandise
returned or reclaimed by Borrower and Borrower's Books relating to any of the
foregoing, as such definition may be amended from time to time according to the
Code.

       "AFFILIATE" of a Person is a Person that owns or controls directly or
indirectly the Person, any Person that controls or is controlled by or is under
common control with the Person, and each of that Person's senior executive
officers, directors, partners and, for any Person that is a limited liability
company, that Person's managers and members.

       "BANK EXPENSES" are all reasonable audit fees and expenses and reasonable
costs or expenses (including reasonable attorneys' fees and expenses) for
preparing, negotiating, administering, defending and enforcing the Loan
Documents (including appeals or Insolvency Proceedings).

                                       17
<Page>

       "BASIC RATE" is, as of the Funding Date the per annum rate of interest
(based on a year of 360 days) equal to the greater of: (i) the Bank's Prime Rate
plus one-quarter of one percent (0.25%), and (ii) five percent (5.00%).

       "BORROWER'S BOOKS" are all Borrower's books and records including
ledgers, records regarding Borrower's assets or liabilities, the Collateral,
business operations or financial condition and all computer programs or discs or
any equipment containing such information.

       "BUSINESS DAY" is any day that is not a Saturday, Sunday or a day on
which the Bank is closed.

       "CAPITALIZATION EVENT" is receipt by the Borrower of net cash proceeds
from the issuance of equity, issued after the Closing Date, from investors
acceptable to Bank and in an amount of at least Five Million Dollars
($5,000,000.00).

       "CLOSING DATE" is the date of this Agreement.

       "CODE" is the Uniform Commercial Code as adopted in Massachusetts, as
amended and as may be amended and in effect from time to time.

       "COLLATERAL" is any and all properties, rights and assets of the Borrower
granted by the Borrower to Bank, now, or in the future, in which the Borrower
obtains an interest, or the power to transfer rights, including, without
limitation, the property described and subject to the exclusions described on
Exhibit A.

       "COMMITMENT TERMINATION DATE" is March 31, 2003. Notwithstanding the
foregoing, the Commitment Termination Date shall be May 30, 2003, upon
confirmation by the Bank that the Capitalization Event has occurred.

       "CONTINGENT OBLIGATION" is, for any Person, any direct or indirect
liability, contingent or not, of that Person for (i) any indebtedness, lease,
dividend, letter of credit or other obligation of another such as an obligation
directly or indirectly guaranteed, endorsed, co-made, discounted or sold with
recourse by that Person, or for which that Person is directly or indirectly
liable; (ii) any obligations for undrawn letters of credit for the account of
that Person; and (iii) all obligations from any interest rate, currency or
commodity swap agreement, interest rate cap or collar agreement, or other
agreement or arrangement designated to protect a Person against fluctuation in
interest rates, currency exchange rates or commodity prices; but "Contingent
Obligation" does not include endorsements in the ordinary course of business.
The amount of a Contingent Obligation is the stated or determined amount of the
primary obligation for which the Contingent Obligation is made or, if not
determinable, the maximum reasonably anticipated liability for it determined by
the Person in good faith; but the amount may not exceed the maximum of the
obligations under the guarantee or other support arrangement.

       "CREDIT EXTENSION" is each Equipment Advance or any other extension of
credit by Bank for Borrower's benefit.

                                       18
<Page>

       "ELIGIBLE EQUIPMENT" is (a) general purpose computer equipment, office
equipment, test and laboratory equipment, furnishings, subject to the
limitations set forth herein, and (b) Other Equipment that complies with all of
Borrower's representations and warranties to Bank and which is acceptable to
Bank in all respects.

       "EQUIPMENT" is all present and future machinery, equipment, tenant
improvements, furniture, fixtures, vehicles, tools, parts and attachments in
which Borrower has any interest.

       "EQUIPMENT ADVANCE" is defined in Section 2.1.1.

       "EQUIPMENT LINE" is an Equipment Advance or Equipment Advances of up to
One Million Two Hundred Thousand Dollars ($1,200,000.00).

       "ERISA" is the Employment Retirement Income Security Act of 1974, and its
regulations. "Event of Loss" is defined in Section 6.8.

       "FINAL PAYMENT" is a payment (in addition to and not a substitution for
the regular monthly payments of principal plus accrued interest) due on the
Maturity Date for such Equipment Advance equal to the Loan Amount for such
Equipment Advance multiplied by the Final Payment Percentage.

       "FINAL PAYMENT PERCENTAGE" is, for each Equipment Advance, eight and
one-half of one percent (8.5%).

       "FINANCED EQUIPMENT" is all present and future Eligible Equipment in
which Borrower has any interest, the purchase of which is financed by an
Equipment Advance.

       "FUNDING DATE" is any date on which an Equipment Advance is made to or on
account of Borrower. "GAAP" is generally accepted accounting principles.

       "INDEBTEDNESS" is (a) indebtedness for borrowed money or the deferred
price of property or services, such as reimbursement and other obligations for
surety bonds and letters of credit, (b) obligations evidenced by notes, bonds,
debentures or similar instruments, (c) capital lease obligations and (d)
Contingent Obligations.

       "INITIAL ADVANCE" is defined in Section 2.1.1(a).

       "INSOLVENCY PROCEEDING" is any proceeding by or against any Person under
the United States Bankruptcy Code, or any other bankruptcy or insolvency law,
including assignments for the benefit of creditors, compositions, extensions
generally with its creditors, or proceedings seeking reorganization,
arrangement, or other relief.

       "INTELLECTUAL PROPERTY" is any copyright rights, copyright applications,
copyright registrations and like protections in each work of authorship and
derivative work, whether published or unpublished, now owned or later acquired;
any patents, patent applications, trademark applications, rights to use,
trademarks, service marks and applications therefor; any

                                       19
<Page>

trade secret rights, including any rights to unpatented inventions, now owned or
hereafter acquired.

       "INVENTORY" is present and future inventory in which Borrower has any
interest, including merchandise, raw materials, parts, supplies, packing and
shipping materials, work in process and finished products intended for sale or
lease or to be furnished under a contract of service, of every kind and
description now or later owned by or in the custody or possession, actual or
constructive, of Borrower, including inventory temporarily out of its custody or
possession or in transit and including returns on any accounts or other proceeds
(including insurance proceeds) from the sale or disposition of any of the
foregoing and any documents of title.

       "INVESTMENT" is any beneficial ownership of (including stock, partnership
interest or other securities) any Person, or any loan, advance or capital
contribution to any Person.

       "LIEN" is a mortgage, lien, deed of trust, charge, pledge, security
interest or other encumbrance.

       "LOAN AMOUNT" in respect of each Equipment Advance is the original
principal amount of such Equipment Advance.

       "LOAN DOCUMENTS" are, collectively, this Agreement, any note, or notes or
guaranties executed by Borrower or Guarantor, and any other present or future
agreement between Borrower and/or for the benefit of Bank in connection with
this Agreement, all as amended, extended or restated, but excluding the Warrant
to Purchase Stock plus other equity documents, if any.

       "LOAN SUPPLEMENT" is defined in Section 2.1.1(b) and attached as EXHIBIT
B.

       "MATERIAL ADVERSE CHANGE" is: (i) A material impairment in the perfection
or priority of Bank's security interest in the Collateral or in the value of
such Collateral; (ii) a material adverse change in the business, operations, or
condition (financial or otherwise) of the Borrower; or (iii) a material
impairment of the prospect of repayment of any portion of the Obligations.

       "MATURITY DATE" is with respect to each Equipment Advance, the last day
of the Repayment Period for such Equipment Advance, or if earlier, the date of
prepayment or the date of acceleration of such Equipment Advance by Bank
following an Event of Default.

       "OBLIGATIONS" are debts, principal, interest, Bank Expenses and other
amounts Borrower owes Bank now or later, under the Loan Documents, and including
interest accruing after Insolvency Proceedings begin.

       "ORIGINAL STATED COST" is (i), the original cost to the Borrower of the
item of new Eligible Equipment net of any and all freight, installation, tax, or
(ii) the fair market value assigned to such item of used Eligible Equipment by
mutual agreement of Borrower and Bank at the time of making of the Equipment
Advance.

                                       20
<Page>

       "OTHER EQUIPMENT" is leasehold improvements, transferable software
licenses, and soft costs approved by the Bank, including sales tax, freight and
installation expenses. Unless otherwise agreed to by Bank, not more than 25% of
the proceeds of the Equipment Line shall be used to finance Other Equipment.

       "PAYMENT DATE" is defined in Section 2.2(a).

       "PERMITTED INDEBTEDNESS" is:

              (a)    Borrower's indebtedness to Bank under this Agreement or the
                     Loan Documents;

              (b)    Indebtedness existing on the Closing Date and shown on the
                     Disclosure Schedule attached hereto;

              (c)    Subordinated Debt;

              (d)    Indebtedness to trade creditors incurred in the ordinary
                     course of business; and

              (e)    Indebtedness secured by Permitted Liens; and

              (f)    Extensions, refinancings, modifications, amendments and
restatements of any items of Permitted Indebtedness (a) through (e) above,
provided that the principal amount thereof is not increased and the terms
thereof are not modified to impose more burdensome terms upon Borrower or its
Subsidiary, as the case may be.

              (g)    Capital leases in an amount not to exceed One Hundred
Thousand Dollars, in the aggregate, during any fiscal year; and

              (h)    Loans to employees in an amount not to exceed Two Hundred
Fifty Thousand Dollars ($250,000.00), in the aggregate, at any time.

       "PERMITTED INVESTMENTS" are:

              (a)    Investments shown on the Disclosure Schedule attached
hereto and existing on the Closing Date; and

              (b)    (i) marketable direct obligations issued or unconditionally
guaranteed by the United States or its agency or any state maturing within 1
year from its acquisition, (ii) commercial paper maturing no more than I year
after its creation and having the highest rating from either Standard & Poor's
corporation or Moody's Investors Service, Inc., (iii) Bank's certificates of
deposit issued maturing no more than 1 year after issue, (iv) any other
investments administered through the Bank.

       "PERMITTED LIENS" are:

                                       21
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              (a)    Liens existing on the Closing Date and shown on the
Perfection Certificate or arising under this Agreement or other Loan Documents;

              (b)    Liens for taxes, fees, assessments or other government
charges or levies, either not delinquent or being contested in good faith and
for which Borrower maintains adequate reserves on its Books, IF they have no
priority over any of Bank's security interests;

              (c)    Purchase money Liens in amount not to exceed One Hundred
Thousand Dollars ($100,000.00), in the aggregate during any fiscal year: (i) on
Equipment acquired or held by Borrower incurred for financing the acquisition of
the Equipment, or (ii) existing on equipment when acquired, IF the Lien is
confined to the property and improvements and the proceeds of the equipment.

              (d)    Leases or subleases and licenses or sublicenses granted in
the ordinary course of Borrower's business or granted in connection with the
consummation of collaborations, joint ventures, or financing arrangements with
the Borrower's business partners in the ordinary course of business, IF the
leases, subleases, licenses and sublicenses permit granting Bank a security
interest; and

              (e)    Liens incurred in the extension, renewal or refinancing of
the indebtedness secured by Liens described in (a) through (d), BUT any
extension, renewal or replacement Lien must be limited to the property
encumbered by the existing Lien and the principal amount of the indebtedness may
not increase unless such increase is itself Permitted Indebtedness.

       "PERSON" is any individual, sole proprietorship, partnership, limited
liability company, joint venture, company, trust, unincorporated organization,
association, corporation, institution, public benefit corporation, firm, joint
stock company, estate, entity or government agency.

       "PRIME RATE" is Bank's most recently announced "prime rate," even if it
is not Bank's lowest rate.

       "REPAYMENT PERIOD" as to each Equipment Advance, is a period of time
equal to thirty six (36) consecutive months commencing on the first Business Day
of the month following the month in which the Funding Date occurs (or commencing
on the Funding Date if the Funding Date is the first Business Day of the month).

       "RESPONSIBLE OFFICER" is each of the Chief Executive Officer and Vice
President for Licensing and Business Development of Borrower.

       "SCHEDULED PAYMENT" is defined in Section 2.2(a).

       "SUBORDINATED DEBT" is debt incurred by Borrower subordinated to
Borrower's debt to Bank (pursuant to a subordination agreement entered into
between the Bank, the Borrower and the subordinated creditor), on terms
acceptable to Bank.

       "SUBSIDIARY" is any Person, corporation, partnership, limited liability
company, joint venture, or any other business entity of which more than 50% of
the voting stock or other equity

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interests is owned or controlled, directly or indirectly, by the Person or one
or more Affiliates of the Person.


       IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed as a sealed instrument under the laws of the Commonwealth of
Massachusetts as of the date first above written.


BORROWER:

MOMENTA PHARMACEUTICALS, INC.

By /s/ Susan K. Whoriskey, Ph.D.
   ---------------------------------------

Name:  Susan K. Whoriskey, Ph.D.

Title:  Vice President, Licensing & Business Development



BANK:

SILICON VALLEY BANK, d/b/a
SILICON VALLEY EAST

By /s/ R. Bryan Jadot
   ---------------------------------------

Name:  R. Bryan Jadot
       -----------------------------------

Title:  Vice President
        ----------------------------------


SILICON VALLEY BANK

By /s/ Maggie Garcia
   -------------------------------------

Name:  Maggie Garcia
       ---------------------------------

Title:  AVP
        --------------------------------
(Signed in Santa Clara County, California)

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