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                                                                   EXHIBIT 10.37

                           SUBSIDIARY PLEDGE AGREEMENT

                  This SUBSIDIARY PLEDGE AGREEMENT (this "Agreement") is dated
as of February 13, 2004 and entered into by and between all Subsidiaries of the
Company that are signatories hereto (each as a "Pledgor" and collectively all
"Pledgors") and Credit Suisse First Boston as Collateral Agent for and
representative of (in such capacity herein called "Secured Party"), the
financial institutions ("Lenders") and agents ("Agents") party to the Credit
Agreement referred to below.

                             PRELIMINARY STATEMENTS

                  A.       Each Pledgor is the legal and beneficial owner of the
shares of stock (the "Pledged Shares") described in Part A of Schedule I annexed
hereto and issued by the corporations named therein.

                  B.       Secured Party, Agents and Lenders have entered into a
Credit Agreement dated as of February 13, 2004 (as amended, supplemented or
otherwise modified from time to time, the "Credit Agreement," the terms defined
therein and not otherwise defined herein being used herein as therein defined)
with Express Scripts, Inc., a Delaware corporation ("Company"), pursuant to
which Lenders have made certain commitments, subject to the terms and conditions
set forth in the Credit Agreement, to extend certain credit facilities to
Company.

                  C.       Pledgor has executed and delivered that certain
Subsidiary Guaranty dated as of February 13, 2004 (as amended, supplemented or
otherwise modified from time to time, the "Guaranty") in favor of Secured Party
for the benefit of Lenders pursuant to which Pledgor has guarantied the prompt
payment and performance when due of all obligations of Company under the Credit
Agreement.

                  D.       It is a condition precedent to the initial extensions
of credit by Lenders under the Credit Agreement that Pledgor shall have granted
the security interests and undertaken the obligations contemplated by this
Agreement.

                  NOW, THEREFORE, in consideration of the premises and in order
to induce Lenders to make Loans and other extensions of credit under the Credit
Agreement, and for other good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, Pledgor hereby agrees with Secured
Party as follows:

                  SECTION 1. PLEDGE OF SECURITY. Pledgor hereby pledges and
assigns to Secured Party, and hereby grants to Secured Party a security interest
in, all of Pledgor's right, title and interest in and to the following (the
"Pledged Collateral"):

                  (a)      the Pledged Shares and the certificates representing
the Pledged Shares and any interest of Pledgor in the entries on the books of
any financial intermediary pertaining to the Pledged Shares, and all dividends,
cash, warrants, rights, instruments and other property or proceeds from time to
time received, receivable or otherwise distributed in respect of or in exchange
for any or all of the Pledged Shares;

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                  (b)      all additional shares of, and all securities
convertible into and warrants, options and other rights to purchase or otherwise
acquire, stock of any issuer of the Pledged Shares from time to time acquired by
Pledgor in any manner (which shares shall be deemed to be part of the Pledged
Shares), the certificates or other instruments representing such additional
shares, securities, warrants, options or other rights and any interest of
Pledgor in the entries on the books of any financial intermediary pertaining to
such additional shares, and all dividends, cash, warrants, rights, instruments
and other property or proceeds from time to time received, receivable or
otherwise distributed in respect of or in exchange for any or all of such
additional shares, securities, warrants, options or other rights;

                  (c)      all shares of, and all securities convertible into
and warrants, options and other rights to purchase or otherwise acquire, stock
of any Person that, after the date of this Agreement, becomes, as a result of
any occurrence, a direct Subsidiary of Pledgor (which shares shall be deemed to
be part of the Pledged Shares), the certificates or other instruments
representing such shares, securities, warrants, options or other rights and any
interest of Pledgor in the entries on the books of any financial intermediary
pertaining to such shares, and all dividends, cash, warrants, rights,
instruments and other property or proceeds from time to time received,
receivable or otherwise distributed in respect of or in exchange for any or all
of such shares, securities, warrants, options or other rights;

                  (d)      to the extent not covered by clauses (a) through (d)
above, all proceeds of any or all of the foregoing Pledged Collateral. For
purposes of this Agreement, the term "proceeds" includes whatever is receivable
or received when Pledged Collateral or proceeds are sold, exchanged, collected
or otherwise disposed of, whether such disposition is voluntary or involuntary,
and includes proceeds of any indemnity or guaranty payable to Pledgor or Secured
Party from time to time with respect to any of the Pledged Collateral.

                  SECTION 2. SECURITY FOR OBLIGATIONS. This Agreement secures,
and the Pledged Collateral is collateral security for, the prompt payment or
performance in full when due, whether at stated maturity, by required
prepayment, declaration, acceleration, demand or otherwise (including the
payment of amounts that would become due but for the operation of the automatic
stay under Section 362(a) of the Bankruptcy Code, 11 U.S.C. Section 362(a)), of
all obligations and liabilities of every nature of Pledgor now or hereafter
existing under or arising out of or in connection with the Guaranty and all
extensions or renewals thereof, whether for principal, interest (including
interest that, but for the filing of a petition in bankruptcy with respect to
Company, would accrue on such obligations, whether or not a claim is allowed
against Company for such interest in the related bankruptcy proceeding),
reimbursement of amounts drawn under Letters of Credit, fees, expenses,
indemnities or otherwise, whether voluntary or involuntary, direct or indirect,
absolute or contingent, liquidated or unliquidated, whether or not jointly owed
with others, and whether or not from time to time decreased or extinguished and
later increased, created or incurred, and all or any portion of such obligations
or liabilities that are paid, to the extent all or any part of such payment is
avoided or recovered directly or indirectly from Secured Party or any Lender as
a preference, fraudulent transfer or otherwise, and all obligations of every
nature of Pledgor now or hereafter existing under this Agreement (all such
obligations of Pledgor being the "Secured Obligations").

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                  SECTION 3. DELIVERY OF PLEDGED COLLATERAL. All certificates or
instruments representing or evidencing the Pledged Collateral shall be delivered
to and held by or on behalf of Secured Party pursuant hereto and shall be in
suitable form for transfer by delivery or, as applicable, shall be accompanied
by Pledgor's endorsement, where necessary, or duly executed instruments of
transfer or assignment in blank, all in form and substance satisfactory to
Secured Party. Upon the occurrence and during the continuation of an Event of
Default (as defined in the Credit Agreement), Secured Party shall have the right
to transfer to or to register in the name of Secured Party or any of its
nominees any or all of the Pledged Collateral, subject only to the revocable
rights specified in Section 7(a); provided that, except in the case of a
bankruptcy default or an acceleration of the Loan, no such transfer or
registration shall be made without notice to Pledgor. In addition, Secured Party
shall have the right at any time to exchange certificates or instruments
representing or evidencing Pledged Collateral for certificates or instruments of
smaller or larger denominations.

                  SECTION 4. REPRESENTATIONS AND WARRANTIES. Pledgor represents
and warrants as follows:

                  (a)      Due Authorization, etc. of Pledged Collateral. All of
the Pledged Shares have been duly authorized and validly issued and are fully
paid and non-assessable.

                  (b)      Description of Pledged Collateral. The Pledged Shares
constitute all of the issued and outstanding shares of stock of each issuer
thereof organized under the laws of a state of the United States (each a "U.S.
Issuer") and 65% of the issued and outstanding shares of stock of each other
issuer thereof (each a "Non-U.S. Issuer"), and there are no outstanding
warrants, options or other rights to purchase, or other agreements outstanding
with respect to, or property that is now or hereafter convertible into, or that
requires the issuance or sale of, any Pledged Shares.

                  (c)      Ownership of Pledged Collateral. Pledgor is the
legal, record and beneficial owner of the Pledged Collateral free and clear of
any Lien except for the security interest created by this Agreement.

                  SECTION 5. TRANSFERS AND OTHER LIENS; ADDITIONAL PLEDGED
COLLATERAL; ETC. Pledgor shall:

                  (a)      not, except as expressly permitted by the Credit
Agreement, (i) sell, assign (by operation of law or otherwise) or otherwise
dispose of, or grant any option with respect to, any of the Pledged Collateral,
(ii) create or suffer to exist any Lien upon or with respect to any of the
Pledged Collateral, except for the security interest under this Agreement, or
(iii) permit any issuer of Pledged Shares to merge or consolidate unless all the
outstanding capital stock of the surviving or resulting corporation is, upon
such merger or consolidation, pledged hereunder and no cash, securities or other
property is distributed in respect of the outstanding shares of any other
constituent corporation; provided that in the event Pledgor makes an Asset Sale
permitted by the Credit Agreement and the assets subject to such Asset Sale are
Pledged Shares, Secured Party shall release the Pledged Shares that are the
subject of such Asset Sale to Pledgor free and clear of the lien and security
interest under this Agreement concurrently with the consummation

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of such Asset Sale; provided, further that, as a condition precedent to such
release, Secured Party shall have received evidence satisfactory to it that
arrangements satisfactory to it have been made for delivery to Secured Party of
the Net Asset Sale Proceeds of such Asset Sale;

                  (b)      (i) cause each issuer of Pledged Shares not to issue
any stock or other securities in addition to or in substitution for the Pledged
Shares issued by such issuer, except to Pledgor, (ii) pledge hereunder,
immediately upon its acquisition (directly or indirectly) thereof, any and all
additional shares of stock or other securities of each issuer of Pledged Shares
except to the extent that such pledge would result in the pledge of more than
65% of the stock of a Non-U.S. Issuer, and (iii) pledge hereunder, immediately
upon its acquisition (directly or indirectly) thereof, any and all shares of
stock of any Person (other than any Exempt Subsidiary) that, after the date of
this Agreement, becomes, as a result of any occurrence, a direct Subsidiary of
Pledgor, unless such subsidiary is a Non-U.S. Issuer, in which case no more than
65% of such shares of stock shall be pledged hereunder;

                  (c)      promptly deliver to Secured Party all written notices
received by it with respect to the Pledged Collateral; and

                  (d)      pay promptly when due all taxes, assessments and
governmental charges or levies imposed upon, and all claims against, the Pledged
Collateral, except to the extent the validity thereof is being contested in good
faith; provided that Pledgor shall in any event pay such taxes, assessments,
charges, levies or claims not later than five days prior to the date of any
proposed sale of the Pledged Collateral under any judgment, writ or warrant of
attachment entered or filed against Pledgor or any of the Pledged Collateral as
a result of the failure to make such payment.

                  SECTION 6. FURTHER ASSURANCES; PLEDGE AMENDMENTS.

                  (a)      Pledgor agrees that from time to time, at the expense
of Pledgor, Pledgor will promptly execute and deliver all further instruments
and documents, and take all further action, that may be necessary or desirable,
or that Secured Party may reasonably request, in order to perfect and protect
any security interest granted or purported to be granted hereby or to enable
Secured Party to exercise and enforce its rights and remedies hereunder with
respect to any Pledged Collateral. Without limiting the generality of the
foregoing, Pledgor will: (i) execute and file such financing or continuation
statements, or amendments thereto, and such other instruments or notices, as may
be necessary or desirable, or as Secured Party may reasonably request, in order
to perfect and preserve the security interests granted or purported to be
granted hereby and (ii) at Secured Party's reasonable request, appear in and
defend any action or proceeding that may affect Pledgor's title to or Secured
Party's security interest in all or any part of the Pledged Collateral.

                  (b)      Pledgor further agrees that it will, upon obtaining
any additional shares of stock or other securities required to be pledged
hereunder as provided in Section 5(b) or (c), promptly (and in any event within
30 days) deliver to Secured Party a Pledge Amendment, duly executed by Pledgor,
in substantially the form of Exhibit I annexed hereto (a "Pledge Amendment"), in
respect of the additional Pledged Shares to be pledged pursuant to this

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Agreement. Pledgor hereby authorizes Secured Party to attach each Pledge
Amendment to this Agreement and agrees that all Pledged Shares listed on any
Pledge Amendment delivered to Secured Party shall for all purposes hereunder be
considered Pledged Collateral; provided that the failure of Pledgor to execute a
Pledge Amendment with respect to any additional Pledged Shares pledged pursuant
to this Agreement shall not impair the security interest of Secured Party
therein or otherwise adversely affect the rights and remedies of Secured Party
hereunder with respect thereto.

                  SECTION 7. VOTING RIGHTS; DIVIDENDS; ETC.

                  (a)      So long as no Event of Default shall have occurred
and be continuing:

                  (i)      Pledgor shall be entitled to exercise any and all
         voting and other consensual rights pertaining to the Pledged Collateral
         or any part thereof for any purpose not inconsistent with the terms of
         this Agreement or the Credit Agreement in a manner which would not have
         a material adverse effect on the value of the Pledged Collateral or any
         part thereof. It is understood, however, that neither (A) the voting by
         Pledgor of any Pledged Shares for or Pledgor's consent to the election
         of directors at a regularly scheduled annual or other meeting of
         stockholders or with respect to incidental matters at any such meeting
         nor (B) Pledgor's consent to or approval of any action otherwise
         permitted under this Agreement and the Credit Agreement shall be deemed
         inconsistent with the terms of this Agreement or the Credit Agreement
         within the meaning of this Section 7(a)(i).

                  (ii)     Pledgor shall be entitled to receive and retain, and
         to utilize free and clear of the lien of this Agreement, any and all
         dividends paid in respect of the Pledged Collateral; provided, however,
         that any and all

                           (A)      dividends paid or payable other than in cash
                  in respect of, and instruments and other property received,
                  receivable or otherwise distributed in respect of, or in
                  exchange for, any Pledged Collateral,

                           (B)      dividends and other distributions paid or
                  payable in cash in respect of any Pledged Collateral in
                  connection with a partial or total liquidation or dissolution
                  or in connection with a reduction of capital, capital surplus
                  or paid-in-surplus, and

                           (C)      cash paid, payable or otherwise distributed
                  in exchange for any Pledged Collateral,

         shall be, and shall forthwith be delivered to Secured Party to hold as,
         Pledged Collateral and shall, if received by Pledgor, be received in
         trust for the benefit of Secured Party, be segregated from the other
         property or funds of Pledgor and be forthwith delivered to Secured
         Party as Pledged Collateral in the same form as so received (with all
         necessary endorsements); and

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                  (iii)    Secured Party shall promptly execute and deliver (or
         cause to be executed and delivered) to Pledgor all such dividend
         payment orders and other instruments as Pledgor may from time to time
         reasonably request for the purpose of enabling Pledgor to receive the
         dividends which it is authorized to receive and retain pursuant to
         paragraph (ii) above.

                  (b)      Upon the occurrence and during the continuation of an
Event of Default:

                  (i)      upon written notice from Secured Party to Pledgor,
         all rights of Pledgor to exercise the voting and other consensual
         rights which it would otherwise be entitled to exercise pursuant to
         Section 7(a)(i) shall cease, and all such rights shall thereupon become
         vested in Secured Party who shall thereupon have the sole right to
         exercise such voting and other consensual rights;

                  (ii)     upon written notice from Secured Party to Pledgor,
         all rights of Pledgor to receive the dividends which it would otherwise
         be authorized to receive and retain pursuant to Section 7(a)(ii) shall
         cease, and all such rights shall thereupon become vested in Secured
         Party who shall thereupon have the sole right to receive and hold as
         Pledged Collateral such dividends; and

                  (iii)    upon written notice from Secured Party to Pledgor,
         all dividends which are received by Pledgor contrary to the provisions
         of paragraph (ii) of this Section 7(b) shall be received in trust for
         the benefit of Secured Party, shall be segregated from other funds of
         Pledgor and shall forthwith be paid over to Secured Party as Pledged
         Collateral in the same form as so received (with any necessary
         endorsements).

                  (c)      In order to permit Secured Party to exercise the
voting and other consensual rights which it may be entitled to exercise pursuant
to Section 7(b)(i) and to receive all dividends and other distributions which it
may be entitled to receive under Section 7(a)(ii) or Section 7(b)(ii), (i)
Pledgor shall promptly execute and deliver (or cause to be executed and
delivered) to Secured Party all such proxies, dividend payment orders and other
instruments as Secured Party may from time to time reasonably request and (ii)
without limiting the effect of the immediately preceding clause (i), Pledgor
hereby grants to Secured Party an irrevocable proxy to vote the Pledged Shares
and to exercise all other rights, powers, privileges and remedies to which a
holder of the Pledged Shares would be entitled (including giving or withholding
written consents of shareholders, calling special meetings of shareholders and
voting at such meetings), which proxy shall be effective, automatically and
without the necessity of any action (including any transfer of any Pledged
Shares on the record books of the issuer thereof) by any other Person (including
the issuer of the Pledged Shares or any officer or agent thereof), upon the
occurrence of an Event of Default and during the continuance thereof and which
proxy shall only terminate upon the payment in full of the Secured Obligations.

                  SECTION 8. SECURED PARTY APPOINTED ATTORNEY-IN-FACT. Pledgor
hereby irrevocably appoints Secured Party as Pledgor's attorney-in-fact, with
full authority in the place and stead of Pledgor and in the name of Pledgor,
Secured Party or otherwise, from time to time in Secured Party's discretion to
take any action and to execute any instrument that Secured Party

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may deem necessary or advisable to accomplish the purposes of this Agreement,
including filing one or more financing or continuation statements, or amendments
thereto, relative to all or any part of the Pledged Collateral without the
signature of Pledgor; provided, that unless an Event of Default has occurred and
is continuing, Secured Party may not (i) receive, endorse and collect any
instruments made payable to Pledgor representing any dividend or other
distribution in respect of the Pledged Collateral or any part thereof; or (ii)
file any claims or take any action or institute any proceedings that Secured
Party may deem necessary or desirable for the collection of any of the Pledged
Collateral or otherwise to enforce the rights of Secured Party with respect to
any of the Pledged Collateral.

                  SECTION 9. SECURED PARTY MAY PERFORM. If Pledgor fails to
perform any agreement contained herein, Secured Party may itself perform, or
cause performance of, such agreement, and the expenses of Secured Party incurred
in connection therewith shall be payable by Pledgor under Section 13(b).

                  SECTION 10. STANDARD OF CARE. The powers conferred on Secured
Party hereunder are solely to protect its interest in the Pledged Collateral and
shall not impose any duty upon it to exercise any such powers. Except for the
exercise of reasonable care in the custody of any Pledged Collateral in its
possession and the accounting for moneys actually received by it hereunder,
Secured Party shall have no duty as to any Pledged Collateral, it being
understood that Secured Party shall have no responsibility for (a) ascertaining
or taking action with respect to calls, conversions, exchanges, maturities,
tenders or other matters relating to any Pledged Collateral, whether or not
Secured Party has or is deemed to have knowledge of such matters, (b) taking any
necessary steps (other than steps taken in accordance with the standard of care
set forth above to maintain possession of the Pledged Collateral) to preserve
rights against any parties with respect to any Pledged Collateral, (c) taking
any necessary steps to collect or realize upon the Secured Obligations or any
guarantee therefor, or any part thereof, or any of the Pledged Collateral, or
(d) initiating any action to protect the Pledged Collateral against the
possibility of a decline in market value. Secured Party shall be deemed to have
exercised reasonable care in the custody and preservation of Pledged Collateral
in its possession if such Pledged Collateral is accorded treatment substantially
equal to that which Secured Party accords its own property consisting of
negotiable securities.

                  SECTION 11. REMEDIES.

                  (a)      If any Event of Default shall have occurred and be
continuing, Secured Party may exercise in respect of the Pledged Collateral, in
addition to all other rights and remedies provided for herein or otherwise
available to it, all the rights and remedies of a secured party on default under
the Uniform Commercial Code as in effect in any relevant jurisdiction (the
"Code") (whether or not the Code applies to the affected Pledged Collateral),
and Secured Party may also in its sole discretion, without notice except as
specified below, sell the Pledged Collateral or any part thereof in one or more
parcels at public or private sale, at any exchange or broker's board or at any
of Secured Party's offices or elsewhere, for cash, on credit or for future
delivery, at such time or times and at such price or prices and upon such other
terms as Secured Party may deem commercially reasonable, irrespective of the
impact of any such sales on the market price of the Pledged Collateral. Secured
Party or any Lender may be the purchaser of any

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or all of the Pledged Collateral at any such sale and Secured Party, as agent
for and representative of Lenders (but not any Lender or Lenders in its or their
respective individual capacities unless Requisite Lenders shall otherwise agree
in writing), shall be entitled, for the purpose of bidding and making settlement
or payment of the purchase price for all or any portion of the Pledged
Collateral sold at any such public sale, to use and apply any of the Secured
Obligations as a credit on account of the purchase price for any Pledged
Collateral payable by Secured Party at such sale. Each purchaser at any such
sale shall hold the property sold absolutely free from any claim or right on the
part of Pledgor, and Pledgor hereby waives (to the extent permitted by
applicable law) all rights of redemption, stay and/or appraisal which it now has
or may at any time in the future have under any rule of law or statute now
existing or hereafter enacted. Pledgor agrees that, to the extent notice of sale
shall be required by law, at least ten Business Days' notice to Pledgor of the
time and place of any public sale or the time after which any private sale is to
be made shall constitute reasonable notification. Secured Party shall not be
obligated to make any sale of Pledged Collateral regardless of notice of sale
having been given. Secured Party may adjourn any public or private sale from
time to time by announcement at the time and place fixed therefor, and such sale
may, without further notice, be made at the time and place to which it was so
adjourned. Pledgor hereby waives any claims against Secured Party arising by
reason of the fact that the price at which any Pledged Collateral may have been
sold at such a private sale was less than the price which might have been
obtained at a public sale, even if Secured Party accepts the first offer
received and does not offer such Pledged Collateral to more than one offeree. If
the proceeds of any sale or other disposition of the Pledged Collateral are
insufficient to pay all the Secured Obligations, Pledgor shall be liable for the
deficiency and the fees of any attorneys employed by Secured Party to collect
such deficiency.

                  (b)      Pledgor recognizes that, by reason of certain
prohibitions contained in the Securities Act and applicable state securities
laws, Secured Party may be compelled, with respect to any sale of all or any
part of the Pledged Collateral conducted without prior registration or
qualification of such Pledged Collateral under the Securities Act and/or such
state securities laws, to limit purchasers to those who will agree, among other
things, to acquire the Pledged Collateral for their own account, for investment
and not with a view to the distribution or resale thereof. Pledgor acknowledges
that any such private sales may be at prices and on terms less favorable than
those obtainable through a public sale without such restrictions (including a
public offering made pursuant to a registration statement under the Securities
Act) and, notwithstanding such circumstances, Pledgor agrees that any such
private sale shall be deemed to have been made in a commercially reasonable
manner and that Secured Party shall have no obligation to engage in public sales
and no obligation to delay the sale of any Pledged Collateral for the period of
time necessary to permit the issuer thereof to register it for a form of public
sale requiring registration under the Securities Act or under applicable state
securities laws, even if such issuer would, or should, agree to so register it.

                  (c)      If Secured Party determines to exercise its right to
sell any or all of the Pledged Collateral, upon written request, Pledgor shall
and shall cause each issuer of any Pledged Shares to be sold hereunder from time
to time to furnish to Secured Party all such information as Secured Party may
request in order to determine the number of shares and other

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instruments included in the Pledged Collateral which may be sold by Secured
Party in exempt transactions under the Securities Act and the rules and
regulations of the Securities and Exchange Commission thereunder, as the same
are from time to time in effect.

                  SECTION 12. APPLICATION OF PROCEEDS. All proceeds received by
Secured Party in respect of any sale of, collection from, or other realization
upon all or any part of the Pledged Collateral shall be applied as provided in
subsection 2.4D of the Credit Agreement.

                  SECTION 13. INDEMNITY AND EXPENSES.

                  (a)      Pledgor agrees to indemnify Secured Party and each
Lender for and against any and all liabilities, obligations, losses, damages,
penalties, actions, judgments, suits, costs, expenses (including reasonable
counsel fees and disbursements) or disbursements of any kind or nature
whatsoever in any way relating to, growing out of or resulting from this
Agreement and the transactions contemplated hereby (including enforcement of
this Agreement), except to the extent such claims, losses or liabilities result
solely from Secured Party's or such Lender's gross negligence or willful
misconduct.

                  (b)      Pledgor shall pay to Secured Party upon demand the
amount of any and all actual and reasonable costs and expenses, including the
reasonable fees and expenses of its counsel and of any experts and agents, that
Secured Party may incur in connection with (i) the administration of this
Agreement, (ii) the custody or preservation of, or the sale of, collection from,
or other realization upon, any of the Pledged Collateral, (iii) the exercise or
enforcement of any of the rights of Secured Party hereunder, or (iv) the failure
by Pledgor to perform or observe any of the provisions hereof.

                  SECTION 14. CONTINUING SECURITY INTEREST; TRANSFER OF LOANS.
This Agreement shall create a continuing security interest in the Pledged
Collateral and shall (a) remain in full force and effect until the payment in
full of all Secured Obligations, the cancellation or termination of the
Commitments and the cancellation or expiration of all outstanding Letters of
Credit, (b) be binding upon Pledgor, its successors and assigns, and (c) inure,
together with the rights and remedies of Secured Party hereunder, to the benefit
of Secured Party and its successors, transferees and assigns. Without limiting
the generality of the foregoing clause (c), but subject to the provisions of
subsection 10.1 of the Credit Agreement, any Lender may assign or otherwise
transfer any Loans held by it to any other Person, and such other Person shall
thereupon become vested with all the benefits in respect thereof granted to
Lenders herein or otherwise. Upon the payment in full of all Secured
Obligations, the cancellation or termination of the Commitments and the
cancellation or expiration of all outstanding Letters of Credit, the security
interest granted hereby shall terminate and all rights to the Pledged Collateral
shall revert to Pledgor. Upon any such termination Secured Party will, at
Pledgor's expense, execute and deliver to Pledgor such documents as Pledgor
shall reasonably request to evidence such termination and Pledgor shall be
entitled to the return, upon its request and at its expense, against receipt and
without recourse to Secured Party, of such of the Pledged Collateral as shall
not have been sold or otherwise applied pursuant to the terms hereof.

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                  SECTION 15. SECURED PARTY AS AGENT.

                  (a)      Secured Party has been appointed to act as Secured
Party hereunder by Lenders. Secured Party shall be obligated, and shall have the
right hereunder, to make demands, to give notices, to exercise or refrain from
exercising any rights, and to take or refrain from taking any action (including
the release or substitution of Pledged Collateral), solely in accordance with
this Agreement and the Credit Agreement; provided that Secured Party shall
exercise, or refrain from exercising, any remedies provided for in Section 11 in
accordance with the instructions of Requisite Lenders.

                  (b)      Secured Party shall at all times be the same Person
that is Administrative Agent under the Credit Agreement. Written notice of
resignation by Administrative Agent pursuant to subsection 9.5 of the Credit
Agreement shall also constitute notice of resignation as Secured Party under
this Agreement; removal of Administrative Agent pursuant to subsection 9.5 of
the Credit Agreement shall also constitute removal as Secured Party under this
Agreement; and appointment of a successor Administrative Agent pursuant to
subsection 9.5 of the Credit Agreement shall also constitute appointment of a
successor Secured Party under this Agreement. Upon the acceptance of any
appointment as Agent under subsection 9.5 of the Credit Agreement by a successor
Administrative Agent, that successor Administrative Agent shall thereupon
succeed to and become vested with all the rights, powers, privileges and duties
of the retiring or removed Secured Party under this Agreement, and the retiring
or removed Secured Party under this Agreement shall promptly (i) transfer to
such successor Secured Party all sums, securities and other items of Collateral
held hereunder, together with all records and other documents necessary or
appropriate in connection with the performance of the duties of the successor
Secured Party under this Agreement, and (ii) execute and deliver to such
successor Secured Party such amendments to financing statements, and take such
other actions, as may be necessary or appropriate in connection with the
assignment to such successor Secured Party of the security interests created
hereunder, whereupon such retiring or removed Secured Party shall be discharged
from its duties and obligations under this Agreement. After any retiring or
removed Administrative Agent's resignation or removal hereunder as Secured
Party, the provisions of this Agreement shall inure to its benefit as to any
actions taken or omitted to be taken by it under this Agreement while it was
Secured Party hereunder.

                  SECTION 16. AMENDMENTS; ETC. No amendment, modification,
termination or waiver of any provision of this Agreement, and no consent to any
departure by Pledgor therefrom, shall in any event be effective unless the same
shall be in writing and signed by Secured Party and, in the case of any such
amendment or modification, by Pledgor. Any such waiver or consent shall be
effective only in the specific instance and for the specific purpose for which
it was given.

                  SECTION 17. NOTICES. Any notice or other communication herein
required or permitted to be given shall be in writing and may be personally
served, telexed or sent by telefacsimile or United States mail or courier
service and shall be deemed to have been given when delivered in person or by
courier service, upon receipt of telefacsimile or telex, or three Business Days
after depositing it in the United States mail with postage prepaid and properly
addressed. For the purposes hereof, the address of each party hereto shall be as
set forth under

                                       10
<PAGE>

such party's name on the signature pages hereof or, as to either party, such
other address as shall be designated by such party in a written notice delivered
to the other party hereto.

                  SECTION 18. FAILURE OR INDULGENCE NOT WAIVER; REMEDIES
CUMULATIVE. No failure or delay on the part of Secured Party in the exercise of
any power, right or privilege hereunder shall impair such power, right or
privilege or be construed to be a waiver of any default or acquiescence therein,
nor shall any single or partial exercise of any such power, right or privilege
preclude any other or further exercise thereof or of any other power, right or
privilege. All rights and remedies existing under this Agreement are cumulative
to, and not exclusive of, any rights or remedies otherwise available.

                  SECTION 19. SEVERABILITY. In case any provision in or
obligation under this Agreement shall be invalid, illegal or unenforceable in
any jurisdiction, the validity, legality and enforceability of the remaining
provisions or obligations, or of such provision or obligation in any other
jurisdiction, shall not in any way be affected or impaired thereby.

                  SECTION 20. HEADINGS. Section and subsection headings in this
Agreement are included herein for convenience of reference only and shall not
constitute a part of this Agreement for any other purpose or be given any
substantive effect.

                  SECTION 21. GOVERNING LAW; TERMS; RULES OF CONSTRUCTION. THIS
AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE
GOVERNED BY, AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH, THE
INTERNAL LAWS OF THE STATE OF NEW YORK. Unless otherwise defined herein or in
the Credit Agreement, terms used in Articles 8 and 9 of the Uniform Commercial
Code in the State of New York are used herein as therein defined. The rules of
construction set forth in subsection 1.3 of the Credit Agreement shall be
applicable to this Agreement mutatis mutandis.

                  SECTION 22. CONSENT TO JURISDICTION AND SERVICE OF PROCESS.
ALL JUDICIAL PROCEEDINGS BROUGHT AGAINST PLEDGOR ARISING OUT OF OR RELATING TO
THIS AGREEMENT, OR ANY OBLIGATIONS HEREUNDER, MAY BE BROUGHT IN ANY STATE OR
FEDERAL COURT OF COMPETENT JURISDICTION IN THE STATE, COUNTY AND CITY OF NEW
YORK. BY EXECUTING AND DELIVERING THIS AGREEMENT, PLEDGOR, FOR ITSELF AND IN
CONNECTION WITH ITS PROPERTIES, IRREVOCABLY

                  (I) ACCEPTS GENERALLY AND UNCONDITIONALLY THE NONEXCLUSIVE
         JURISDICTION AND VENUE OF SUCH COURTS;

                  (II) WAIVES ANY DEFENSE OF FORUM NON CONVENIENS WITH RESPECT
         TO ANY STATE OR FEDERAL COURT OF COMPETENT JURISDICTION IN THE STATE,
         COUNTY AND CITY OF NEW YORK;

                  (III) AGREES THAT SERVICE OF ALL PROCESS IN ANY SUCH
         PROCEEDING IN ANY SUCH COURT MAY BE MADE BY REGISTERED OR

                                       11
<PAGE>

         CERTIFIED MAIL, RETURN RECEIPT REQUESTED, TO PLEDGOR AT ITS ADDRESS
         PROVIDED IN ACCORDANCE WITH SECTION 18;

                  (IV) AGREES THAT SERVICE AS PROVIDED IN CLAUSE (III) ABOVE IS
         SUFFICIENT TO CONFER PERSONAL JURISDICTION OVER PLEDGOR IN ANY SUCH
         PROCEEDING IN ANY SUCH COURT, AND OTHERWISE CONSTITUTES EFFECTIVE AND
         BINDING SERVICE IN EVERY RESPECT;

                  (V) AGREES THAT SECURED PARTY RETAINS THE RIGHT TO SERVE
         PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR TO BRING PROCEEDINGS
         AGAINST PLEDGOR IN THE COURTS OF ANY OTHER JURISDICTION; AND

                  (VI) AGREES THAT THE PROVISIONS OF THIS SECTION 23 RELATING TO
         JURISDICTION AND VENUE SHALL BE BINDING AND ENFORCEABLE TO THE FULLEST
         EXTENT PERMISSIBLE UNDER NEW YORK GENERAL OBLIGATIONS LAW SECTION
         5-1402 OR OTHERWISE.

                  SECTION 23. WAIVER OF JURY TRIAL. PLEDGOR AND SECURED PARTY
HEREBY AGREE TO WAIVE THEIR RESPECTIVE RIGHTS TO A JURY TRIAL OF ANY CLAIM OR
CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT. The scope of this
waiver is intended to be all-encompassing of any and all disputes that may be
filed in any court and that relate to the subject matter of this transaction,
including contract claims, tort claims, breach of duty claims, and all other
common law and statutory claims. Pledgor and Secured Party each acknowledge that
this waiver is a material inducement for Pledgor and Secured Party to enter into
a business relationship, that Pledgor and Secured Party have already relied on
this waiver in entering into this Agreement and that each will continue to rely
on this waiver in their related future dealings. Pledgor and Secured Party
further warrant and represent that each has reviewed this waiver with its legal
counsel, and that each knowingly and voluntarily waives its jury trial rights
following consultation with legal counsel. THIS WAIVER IS IRREVOCABLE, MEANING
THAT IT MAY NOT BE MODIFIED EITHER ORALLY OR IN WRITING (OTHER THAN BY A MUTUAL
WRITTEN WAIVER SPECIFICALLY REFERRING TO THIS SECTION 24 AND EXECUTED BY EACH OF
THE PARTIES HERETO), AND THIS WAIVER SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS,
RENEWALS, SUPPLEMENTS OR MODIFICATIONS TO THIS AGREEMENT. In the event of
litigation, this Agreement may be filed as a written consent to a trial by the
court.

                  SECTION 24. COUNTERPARTS. This Agreement may be executed in
one or more counterparts and by different parties hereto in separate
counterparts, each of which when so executed and delivered shall be deemed an
original, but all such counterparts together shall constitute but one and the
same instrument; signature pages may be detached from multiple separate
counterparts and attached to a single counterpart so that all signature pages
are physically attached to the same document.

                                       12
<PAGE>

                  [Remainder of page intentionally left blank]

                                       13
<PAGE>

                  IN WITNESS WHEREOF, Pledgors and Secured Party have caused
this Agreement to be duly executed and delivered by their respective officers
thereunto duly authorized as of the date first written above.

                                        CENTRAL FILL, INC.
                                        CFI OF NEW JERSEY, INC.
                                        CURASCRIPT PHARMACY, INC.
                                        CURASCRIPT PBM SERVICES, INC.
                                        DIVERSIFIED PHARMACEUTICAL
                                          SERVICES, INC.
                                        EXPRESS SCRIPTS SALES
                                        DEVELOPMENT CO.
                                        IBIOLOGIC, INC.
                                        IVTX, INC.
                                        VALUE HEALTH, INC.
                                        ESI MAIL PHARMACY SERVICE, INC.
                                        EXPRESS SCRIPTS UTILIZATION
                                          MANAGEMENT CO.
                                        EXPRESS SCRIPTS SPECIALTY
                                          DISTRIBUTION SERVICES, INC.
                                        ESI AIRPORT PROPERTIES, LLC
                                        ESI CLAIMS, INC.
                                        ESI ENTERPRISES, LLC
                                        ESI PARTNERSHIP
                                        ESI REALTY, LLC
                                        NATIONAL PRESCRIPTION
                                          ADMINISTRATORS, INC.
                                        PHOENIX MARKETING GROUP, L.L.C.
                                        EXPRESS SCRIPTS CANADA HOLDING
                                          CO.
                                        YOURPHARMACY.COM, INC.

                                        Each as a Pledgor

                                        By: /s/ George Paz
                                           -------------------------------------
                                           Name: George Paz
                                           Title: Vice President

                                        ESI RESOURCES, INC.

                                        ESI-GP HOLDINGS, INC.

                                        Each as a Pledgor

                                        By: /s/ Thomas L. Schaefer
                                           -------------------------------------

                                       14
<PAGE>

                                             Name: Thomas L. Schaefer
                                             Title:  President

                                        Notice Address:

                                        13900 Riverport Drive
                                        Maryland Heights, Missouri  63043
                                        Attention:  Michael Salamone

                                       15
<PAGE>


                                        CREDIT SUISSE FIRST BOSTON,
                                          as Secured Party

                                        By: /s/ Joseph Adipietro
                                           -------------------------------------
                                           Name: Joseph Adipietro
                                           Title: Director

                                        By: /s/ Kingsbury
                                           -------------------------------------
                                           Name: Kingsbury
                                           Title: Director

                                        Notice Address:

                                        Eleven Madison Avenue
                                        New York, New York  10010
                                        Attention:

                                       16
<PAGE>

                                   SCHEDULE I

                  Attached to and forming a part of the Pledge Agreement dated
as of February 13, 2004 between each of the Pledgors party thereto, and Credit
Suisse First Boston, as Secured Party.

                                     PART A

                  Pledgor: CURASCRIPT PBM SERVICES, INC.

<TABLE>
<CAPTION>
                                                           Stock Certificate                          Number of
 Stock Issuer                         Class of Stock              Nos.               Par Value          Shares
---------------                       --------------       -----------------         ---------        ---------
<S>                                   <C>                  <C>                       <C>              <C>
iBIOLogic, Inc.                          Common                   C1                   $.01             1,000
</TABLE>

                  Pledgor: ESI MAIL PHARMACY SERVICE, INC.

<TABLE>
<CAPTION>
                                                           Stock Certificate                         Number of
    Stock Issuer                     Class of Stock              Nos.               Par Value          Shares
----------------------               --------------        -----------------        ---------        ---------
<S>                                   <C>                  <C>                     <C>               <C>
Central Fill, Inc.                       Common                   10                  $1.00             3,000
CFI of New Jersey, Inc.                  Common                  CA11              No Par Value         2,004
                                         Common                  C19               No Par Value          996
ESI Enterprises, LLC                   Membership                N/A                   N/A               49%
                                        Interest
</TABLE>

                  Pledgor: ESI PARTNERSHIP

<TABLE>
<CAPTION>
                                                          Stock Certificate                          Number of
   Stock Issuer                       Class of Stock             Nos.               Par Value          Shares
----------------------               --------------        -----------------        ---------        ---------
<S>                                  <C>                  <C>                       <C>              <C>
ESI Resources, Inc.                      Common                   1                   $1.00             1,000
</TABLE>

                  Pledgor: ESI-GP HOLDINGS, INC.

<TABLE>
<CAPTION>
                                                           Stock Certificate                         Number of
  Stock Issuer                       Class of Stock              Nos.               Par Value          Shares
----------------------               --------------        -----------------        ---------        ---------
<S>                                  <C>                   <C>                      <C>              <C>
ESI Partnership                         General                  N/A                   N/A          18% Interest
                                      Partnership
                                        Interest

ESI Enterprises, LLC                   Membership                N/A                   N/A               1%
                                        Interest
</TABLE>

                                       17
<PAGE>

                  Pledgor: EXPRESS SCRIPTS SPECIALTY DISTRIBUTION SERVICES, INC.

<TABLE>
<CAPTION>
                                                           Stock Certificate                          Number of
    Stock Issuer                     Class of Stock              Nos.                Par Value          Shares
----------------------               --------------        -----------------        ---------        ---------
<S>                                  <C>                   <C>                      <C>              <C>
ESI Enterprises, LLC                   Membership                N/A                   N/A               20%
                                        Interest
</TABLE>

                  The following Pledgors do not have Pledged Shares or Pledged
Collateral:

         Central Fill, Inc.

         CFI of New Jersey, Inc.

         CuraScript Pharmacy, Inc.

         Diversified Pharmaceutical Services, Inc.

         ESI Airport Properties, L.L.C.

         ESI Claims, Inc.

         ESI Enterprises, LLC

         ESI Realty, L.L.C.

         ESI Resources, Inc.

         Express Scripts Canada Holding Co.

         Express Scripts Sales Development Co.

         Express Scripts Utilization Management Co.

         iBIOLogic, Inc.

         IVTx, Inc.

         National Prescription Administrators, Inc.

         Phoenix Marketing Group, L.L.C.

         Value Health, Inc.

         YourPharmacy, Inc.

                                       18
<PAGE>

                                    EXHIBIT I

                                PLEDGE AMENDMENT

                  This Pledge Amendment, dated __________, ____, is delivered
pursuant to Section 6(b) of the Pledge Agreement referred to below. The
undersigned hereby agrees that this Pledge Amendment may be attached to the
Pledge Agreement dated February 13, 2004, between the Pledgors party thereto and
Credit Suisse First Boston, as Secured Party (the "Pledge Agreement,"
capitalized terms defined therein being used herein as therein defined), and
that the Pledged Shares listed on this Pledge Amendment shall be deemed to be
part of the Pledged Shares and shall become part of the Pledged Collateral and
shall secure all Secured Obligations.

                                        [NAME OF PLEDGOR]

                                        By:  ___________________________________
                                        Title:__________________________________

<TABLE>
<CAPTION>
                                                  Stock Certificate                             Number of
Stock Issuer               Class of Stock                Nos.                  Par Value          Shares
------------               -------------          -----------------            ---------        ---------
<S>                        <C>                    <C>                          <C>              <C>

</TABLE>

                                       19