<PAGE>

                                                                   Exhibit 10.34
--------------------------------------------------------------------------------
[LOGO OF GREYROCK CAPITAL APPEARS HERE]

                          LETTER OF CREDIT AGREEMENT

BORROWER:  PRIME RESPONSE U.S., INC.
           (FORMERLY KNOWN AS PRIME RESPONSE, INC.)

ADDRESS:   150 CAMBRIDGE PARK DRIVE
           CAMBRIDGE, MASSACHUSETTS  02140

DATE:      NOVEMBER 24, 1999

     THIS LETTER OF CREDIT AGREEMENT ("Agreement"), dated the above date, is
entered into between GREYROCK CAPITAL, a Division of Banc of America Commercial
Finance Corporation ("GC") and the borrower named above ("Borrower"), in
connection with the Loan and Security Agreement ("Loan Agreement") between GC
and Borrower dated October 28, 1999. This Agreement is an integral part of the
Loan Agreement, and all of the terms and provisions of the Loan Agreement are
incorporated herein by this reference. (Capitalized terms used in this
Agreement, which are not defined in this Agreement, shall have the meanings set
forth in the Loan Agreement. This Agreement, the Loan Agreement and all other
present and future documents instruments and agreements between GC and the
Borrower are referred to herein collectively as the "Loan Documents."

   1.  LETTERS OF CREDIT.  From time to time, in order to assist Borrower in
establishing or opening Letters of Credit (the "LCs") with a bank, trust company
or other issuer ("Bank") to cover the purchase of goods or for other purposes,
including the provision of overdraft facilities, Borrower may request that GC
join in the applications for the LCs, and/or provide guarantees of, and/or
indemnities with respect to, payment or performance of the LCs and/or any drafts
or acceptances thereunder and/or Borrower's obligations in connection therewith
(collectively, "Guarantees"). The decision to do so shall be a matter of GC's
sole discretion. In the event GC joins in such applications and/or provides
Guarantees, the transactions shall be subject to the terms and conditions of
this Agreement. The amount, extent, terms and conditions of the LCs and any
drafts or acceptance relating thereto, shall in all respects be determined
solely by GC and shall be subject to change, modification and revision by GC at
any time and from time to time, in its discretion.

   2.  INDEMNITY.  Borrower unconditionally agrees to indemnify, defend and hold
GC harmless from any and all indebtedness, liabilities, obligations, losses and
claims, of every sort whatsoever, however arising, whether present or future,
fixed or contingent, due or to become due, paid or incurred, arising, incurred
in connection with, or relating to, any LCs, applications for LCs, Guarantees,
drafts or acceptances thereunder or LC Collateral (as defined below), including
without limitation (i) any and all losses and claims due to any action or
omission by any Bank, any errors or omissions of GC or any Bank, or otherwise,
(ii) all amounts due or which may become due under LCs, or any drafts or
acceptances thereunder, (iii) all liabilities and obligations under any
steamship or airway guarantees or releases or any Guarantees, (iv) all amounts
charged or chargeable to Borrower or to GC by any Bank, any other financial
institution or any correspondent bank which opens, issues or is involved with
the LCs, (v) all other bank charges, and (vi) all fees, commissions, duties,
taxes, costs of insurance, and all such other charges and expenses which may
pertain either directly or indirectly to any LC, draft, acceptance, or Guarantee
or to the goods or documents relating thereto (except any such amounts sustained
or incurred as the result of the gross negligence or willful misconduct of GC or
any of its
<PAGE>

directors, officers, employees, agents, attorneys, or any other person
affiliated with or representing GC). Borrower's obligation to indemnify GC under
this Agreement and Borrower's other obligations under this Agreement are
referred to herein as the "LC Obligations" (which shall include, without
limitation, the aggregate face amounts of all LCs and Guarantees). Borrower's LC
Obligations shall not be modified or diminished for any reason or in any manner
whatsoever, shall be included in the "Obligations" (as defined in the Loan
Agreement), and shall survive termination of the Loan Agreement and any other
Loan Document. Without limiting the generality of the foregoing, Borrower agrees
that any charges made to GC by any Bank for Borrower's account or relating to
any LC shall be conclusive on Borrower and may be charged to any of Borrower's
Loan accounts with GC. GC shall have the right, at any time and without notice
to Borrower, to charge any of Borrower's Loan accounts with GC with the amount
of any and all sums due from Borrower to GC under this Agreement, and the same
shall constitute Loans for all purposes of the Loan Documents and shall bear
interest at the rate provided in the Loan Agreement. All sums payable by
Borrower to GC under this Agreement shall be paid solely in United States
dollars.

   3.  LC LIMITS.  Without limiting the fact that GC's decisions to join in
an application for an LC or issue a Guarantee are a matter of its sole
discretion, the total amount of all outstanding LC Obligations shall not at any
time exceed $1,000,000 in the aggregate, and if for any reason they do, Borrower
shall provide cash collateral to GC in an amount equal to the excess, to secure
all of the Obligations, and Borrower shall execute and deliver to GC a pledge
agreement with respect thereto on GC's standard form.  In addition, the total
amount of all LC Obligations and all outstanding "Loans" and other "Obligations"
(as defined in the Loan Agreement) shall not at any time exceed the maximum
amount of all Loans and other Obligations specified in Section 1.1 of the Loan
Agreement, and if for any reason they do, Borrower shall immediately pay the
excess to GC to be applied to the Obligations in such order and manner as GC
shall determine in its sole discretion.

   4. LOAN AVAILABILITY RESERVE.  The amount of Loans which would otherwise
be available to Borrower from time to time under the lending formulas set forth
in the Loan Agreement and the other Loan Documents shall be reduced by 100% of
the total amount of all LC Obligations from time to time outstanding.

   5. CHARGES.  In addition to any charges, fees or expenses of any Bank or
other person in connection with any LC (all of which shall be charged to
Borrower's Loan account), GC shall be entitled to charge Borrower's Loan account
with a fee in an amount equal to three percent (3%) per annum of the amount of
all LC Obligations from time to time outstanding, calculated on the basis of a
360-day year for the actual number of days elapsed.

   6. SECURITY.  Without limiting the security interests granted in the Loan
Documents, Borrower hereby grants GC a security interest in the following (the
"LC Collateral"), whether now owned or hereafter acquired by Borrower, wherever
located, whether in transit or not, to secure all of the Obligations:  all bills
of lading, shipping documents, documents of title, chattel paper, invoices,
cash, checks, drafts, notes, documents, warehouse, shipping and dock receipts,
and other title, payment, or other instruments, and instruments, whether
negotiable or not, relating to any LC, and all goods and inventory relating
thereto in all stages of manufacture, process or production, and all cash and
non-cash proceeds and insurance proceeds thereof of whatever sort and however
arising.  All references in the Loan Agreement to "Collateral" shall, for all
purposes, include without limitation the LC Collateral, and all terms and
provisions of the Loan Agreement applicable to Collateral shall also apply to
the LC Collateral.

   7. NON-RESPONSIBILITY.  GC shall not be responsible for: the existence,
character, quality, quantity, condition, packing, value or delivery of the goods
purporting to be represented by any documents; any difference or variation in
the character, quality, quantity, condition, packing, value or delivery of the
goods from that expressed in the documents; the validity, sufficiency or
genuineness of any documents or of any endorsements thereon, even if such
documents should in fact prove to be in any or all respects invalid,
insufficient, fraudulent or forged; the time, place, manner or order in which
shipment is made; partial or incomplete shipment, or failure or omission to ship
any or all of the goods referred to in the LCs or documents; any deviation from
instructions, delay, default, or fraud by the shipper and/or anyone else in
connection with the LC Collateral or the shipping thereof; or any breach of
contract between the shipper or vendors and Borrower. Furthermore, without being
limited by the foregoing, GC shall not be responsible for any act or omission
with respect to or in connection with any LC Collateral.

                                      -2-
<PAGE>

   8. GC'S AUTHORITY.  Borrower agrees that any action taken by GC, if taken in
good faith, or any action taken by any Bank, under or in connection with the
LCs, the Guarantees, the drafts or acceptances, or the LC Collateral, shall be
binding on Borrower and shall not result in any liability of GC to Borrower. In
furtherance thereof, GC shall have the full right and authority to clear and
resolve any questions of non-compliance of documents; to give any instructions
as to acceptance or rejection of any documents or goods; to execute any and all
applications for steamship or airway guarantees, indemnities or delivery orders;
to grant any extensions of the maturity of, time or payment for, or time of
presentation of, any drafts, acceptances, or documents; and to agree to any
amendments, renewals, extensions, modifications, changes or cancellations of any
of the terms or conditions of any of the applications, LCs, drafts or
acceptances; all in GC's sole name, and the Bank shall be entitled to comply
with and honor any and all such documents or instruments executed by or received
solely from GC, all without any notice to or any consent from Borrower.

   9. GC'S RIGHTS.  Any rights, remedies, duties or obligations granted or
undertaken by Borrower to any Bank in any application for LCs, or any standing
agreement relating to LCs or otherwise, shall be deemed to have been granted to
GC and apply in all respects to GC and shall be in addition to any rights,
remedies, duties or obligations contained herein. Borrower hereby agrees that
prior to the payment of all Obligations to GC, GC may be deemed to be the
absolute owner of, with unqualified rights to possession and disposition of, all
LC Collateral, all of which may be held by GC as security as herein provided.
Should possession of any LC Collateral be transferred to Borrower, said LC
Collateral shall continue to serve as security as herein provided, and any goods
or inventory covered hereby may be sold, transferred or disposed of only as
permitted by the Loan Documents.

  10. NEGATIVE COVENANTS.  Without GC's prior written approval, Borrower agrees
not to clear or resolve any questions of non-compliance of documents; not to
give any instructions as to acceptance or rejection of any documents or goods;
not to execute any applications for steamship or airway guarantees, indemnities
or delivery orders; not to grant any extensions of the maturity of, time of
payment for, or time of presentation of, any drafts, acceptances or documents;
and not to agree to any amendments, renewals, extensions, modifications, changes
or cancellations of any of the terms or conditions of any of the applications,
LCs, drafts or acceptances.

  11. AFFIRMATIVE COVENANTS.  Borrower shall cause:  all necessary import,
export or other licenses or certificates for the import or handling of the LC
Collateral to be promptly procured; all foreign and domestic governmental laws
and regulations in regard to the shipment and importation of the LC Collateral,
or the financing thereof to be promptly and fully complied with; and any
certificates in that regard that GC may at any time request to be promptly
furnished.  In this connection, Borrower warrants and represents to GC that all
shipments made under the LCs are and shall be in accordance with the
governmental laws and regulations of the countries in which the shipments
originate and terminate, and shall not be prohibited by any such laws or
regulations.  Borrower assumes all risk, liability and responsibility for, and
agrees to pay and discharge, all present and future local, state, federal or
foreign taxes, duties, and levies.  Any embargo, restriction, laws, customs or
regulations of any country, state, city, or other political subdivision, where
the Collateral is or may be located, or wherein payments are to be made, or
wherein drafts may be drawn, negotiated, accepted, or paid, shall be solely
Borrower's risk, liability and responsibility.

  12. TERMINATION.  Without limiting any of the terms of the Loan Agreement,
on the effective date of termination of the Loan Agreement, in addition to
paying and performing in full all other Obligations, Borrower shall provide cash
collateral to GC in an amount equal to 110% of the amount of all LC Obligations,
to secure all of the Obligations, and Borrower shall execute and deliver to GC a
pledge agreement with respect thereto on GC's standard form.  (If the Loan
Agreement provides for a lesser amount of cash collateral, this Agreement shall
control.)

  13. DEFAULT.  On any failure to pay or perform any Obligation when due, or
the occurrence of any other "Event of Default" (as defined in the Loan
Agreement), GC shall have all of the rights and remedies set forth in the Loan
Documents and which it otherwise has under applicable law, and without limiting
the generality of the foregoing, GC shall have the right to require Borrower to
deposit cash collateral with GC in an amount equal to 110% of the amount of all
LC Obligations, to secure all of the Obligations, and Borrower shall execute and
deliver to GC a pledge agreement with respect thereto on GC's standard form.

                                      -3-
<PAGE>

  14. POWER OF ATTORNEY.  Without limiting the terms of any of the Loan
Documents, Borrower hereby appoints each employee, attorney or agent of GC as
Borrower's attorney-in-fact, with full power and authority in each of them, at
GC's option, but without obligation, with or without notice to Borrower, in
connection with any LC and any purchase agreement or other document or agreement
entered into, or goods delivered, in connection therewith, at Borrower's
expense, to do any or all of the following in Borrower's name or otherwise:  (i)
to sign or endorse all warehouse, shipping, dock or other receipts, letters of
credit,  notes, acceptances, checks, drafts, money orders and all other evidence
of indebtedness, and all financing statements, invoices, trust receipts, bills
of lading and other title documents; (ii) to complete any transaction in
connection with, arising out of, or which is the subject of any LC or Guarantee,
to obtain, execute and deliver all necessary or proper documents in connection
therewith and to collect the proceeds thereof; (iii) upon any Event of Default
under the Loan Agreement, or this Agreement, to cancel, rescind, terminate,
modify, amend, or adjust, in any other way, in whole or in part, any transaction
in connection with, arising out of, or which is the subject of any LC or
Guarantee; and (iv) to do any and all other acts and things which may be
necessary or appropriate in connection with this Agreement or any LC, or any
transaction relating thereto, or to enable GC to obtain payment of any
Obligations.  The power of attorney granted hereunder is coupled with an
interest and shall be irrevocable until all Obligations have been paid in full.

  15. GENERAL.  Without limiting any of the other provisions of this
Agreement, all of the General Provisions of Section 9 of the Loan Agreement, as
well as all other provisions of the Loan Agreement, are hereby incorporated
herein by this reference.

  16. MUTUAL WAIVER OF JURY TRIAL.  BORROWER AND GC EACH HEREBY WAIVE THE
RIGHT TO TRIAL BY JURY IN ANY ACTION OR PROCEEDING BASED UPON, ARISING OUT OF,
OR IN ANY WAY RELATING TO, THIS AGREEMENT OR ANY OTHER PRESENT OR FUTURE
INSTRUMENT OR AGREEMENT BETWEEN GC AND BORROWER, OR ANY CONDUCT, ACTS OR
OMISSIONS OF GC OR BORROWER OR ANY OF THEIR DIRECTORS, OFFICERS, EMPLOYEES,
AGENTS, ATTORNEYS OR ANY OTHER PERSONS AFFILIATED WITH GC OR BORROWER, IN ALL OF
THE FOREGOING CASES, WHETHER SOUNDING IN CONTRACT OR TORT OR OTHERWISE.


BORROWER:

  PRIME RESPONSE U.S., INC.

  BY /s/ Jamie Gunn
    ----------------------------------
        PRESIDENT OR VICE PRESIDENT

  BY /s/ Jamie Gunn
    ----------------------------------
       SECRETARY OR ASS'T SECRETARY


GC:

  GREYROCK CAPITAL,
  A DIVISION OF BANC OF AMERICA
  COMMERCIAL FINANCE CORPORATION

  BY: /s/ Lisa Nagano
     ---------------------------------
  TITLE Senior Vice President
        ------------------------------

                                      -4-