<PAGE>

                        Mortgage Loan Purchase Agreement

                   Mortgage Loan Purchase Agreement (the "Agreement"), dated as
of July 27, 2001 between Washington Mutual Mortgage Securities Corp. (the
"Seller") and ABN AMRO Mortgage Corporation (the "Purchaser").

                   Subject to the terms and conditions of this Agreement, the
Seller agrees to sell and the Purchaser agrees to purchase certain mortgage
loans (the "Mortgage Loans") as described herein and as identified on the
Mortgage Loan Schedule defined in Section 2 hereof. The Mortgage Loans will be
purchased on a servicing released basis.

                   Now, therefore, in consideration of the premises and the
mutual agreements set forth herein, the parties agree as follows:

          SECTION 1. Purchase and Sale of the Mortgage Loans.

          (a) Pursuant to the terms hereof and upon satisfaction of the
conditions set forth herein, the Seller agrees to sell and the Purchaser agrees
to purchase, Mortgage Loans having the general characteristics set forth in this
Agreement and specifically identified on the Mortgage Loan Schedule, for the
Purchase Price set forth below in Section 3(a) hereof and having an aggregate
principal balance on and as of the date of such Mortgage Loan Schedule (the
"Cut-Off Date") of approximately $343,394,509 after deduction of principal
payments due on or before the Cut-Off Date (which amount may vary plus or minus
5% thereof), or such other aggregate principal balance as agreed by the
Purchaser and the Seller as evidenced by the actual aggregate principal balance
of the Mortgage Loans accepted by the Purchaser on the Closing Date (as defined
below).

          (b) Subject to mutual agreement between the Purchaser and the Seller,
the closing for the purchase and sale of the Mortgage Loans shall take place on
July 27, 2001 (the "Closing Date") at the office of Purchaser's counsel in
Chicago, Illinois or such other place as the parties shall agree.

          SECTION 2. Mortgage Loan Schedule. Attached to this Agreement as
Schedule 1 is a listing of the Mortgage Loans evidenced by promissory notes,
mortgage notes or other evidence of indebtedness (the "Mortgage Notes")
evidencing the indebtedness of an obligor (the "Mortgagor") under the mortgages,
deeds of trust or other instruments securing a Mortgage Loan (the "Mortgages")
to be purchased by and delivered to the Purchaser on the Closing Date (as such
may be amended prior to the Closing Date by mutual agreement of the parties)
(the "Mortgage Loan Schedule"). The "Mortgage Loan Schedule" as of the Closing
Date shall refer to the Mortgage Loan Schedule as delivered on the Cut-Off Date
related to such Mortgage Loans to be purchased by or on behalf of the Purchaser
pursuant to the terms of this Agreement. The Mortgage Loan Schedule shall
contain as to each Mortgage Loan listed thereon, at a minimum, the Mortgage Loan
information indicated on Schedule 2 hereto.



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          SECTION 3. Purchase Price.

          (a) In exchange for the Mortgage Loans, on the Closing Date, the
Purchaser shall transfer to the Seller by wire transfer in immediately available
funds the purchase price (the "Purchase Price") which is equal to the sum of (a)
the product of 100.0148% and the principal balance thereof as of the Cut-Off
Date and (b) interest on the principal balance of the Mortgage Loans as of the
Cut- Off Date at the Pass-Through Rate from the Cut-Off Date through the day
prior to the Closing Date. With respect to each Mortgage Loan, the "Pass-Through
Rate" shall be the mortgage interest rate on such Mortgage Loan less the per
annum servicing fee payable to the Seller pursuant to the Pooling Agreement (as
defined below). As additional consideration for the Mortgage Loans, the
Purchaser shall enter into, and shall cause State Street Bank and Trust Company,
as trustee, to enter into, a Pooling and Servicing Agreement (the "Pooling
Agreement") with the Seller, which Pooling Agreement shall be reasonably
satisfactory to the Seller in form and substance, pursuant to which the Seller
shall have the right to service each Mortgage Loan for a servicing fee ranging
from 0.29% to .099% per annum, with a weighted average of 0.561% per annum. The
Pooling Agreement shall be executed simultaneously with the execution of this
Agreement.

          (b) The Purchaser shall be entitled to all scheduled payments of
principal and interest due with respect to the Mortgage Loans after the Cut-Off
Date, and all other recoveries of principal and interest collected after the
Cut-Off Date (other than in respect of principal and interest on the Mortgage
Loans due on or before the Cut-Off Date). The Seller shall be entitled to all
scheduled payments of principal and interest due with respect to the Mortgage
Loans on or before the Cut-Off Date, and all other recoveries of principal and
interest collected on or before the Cut-Off Date (other than in respect of
principal and interest on the Mortgage Loans due after the Cut-Off Date). The
principal balance of each Mortgage Loan as of the Cut-Off Date is determined
after deduction of payments of principal due on or before the Cut-Off Date
whether or not collected. Therefore, payments of scheduled principal and
interest prepaid for a date due following the Cut-Off Date shall not be deducted
from the principal balance as of the Cut-Off Date but such prepaid amounts shall
belong to and be promptly remitted to the Purchaser.

          SECTION 4. Examination of Mortgage Files.

          Prior to the Closing Date, the Seller will have made files for each
Mortgage Loan, that consist at least of the documents listed on Schedule 3
attached hereto (with respect to each Mortgage Loan, a "Mortgage File", and
collectively, the "Mortgage Files"), available to the Purchaser or its agents,
for examination at the Seller's offices or such other location as shall
otherwise be agreed upon by the Purchaser and the Seller. The Purchaser may
purchase all or part of the Mortgage Loans with or without conducting any
partial or complete examination. The fact that the Purchaser or its agents have
conducted or have failed to conduct any partial or complete examination of the
Mortgage Files shall not affect the Purchaser's rights under this Agreement,
including, but not limited to, the rights to demand repurchase, substitution or
other relief as provided in this Agreement.



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          SECTION 5. Transfer of Mortgage Loans; Possession of Mortgage Files.

          (a) On the Closing Date, subject to the satisfaction of the terms and
conditions hereof, the Seller shall sell, transfer, assign, set over and
otherwise convey to the Purchaser, without recourse, but subject to the terms of
this Agreement, all right, title and interest of the Seller in and to the
Mortgage Loans and all proceeds thereof, wherever located, including without
limitation, all amounts in respect of principal and interest received or
receivable with respect to Mortgage Loan payments due after the Cut-Off Date
(and including scheduled payments of principal and interest due after the
Cut-Off Date but received by the Seller on or before the Cut-Off Date, but not
including payments of principal and interest due on the Mortgage Loans on or
before the Cut-Off Date), together with the proceeds of any related mortgage
insurance policies. Such transfer shall be made directly to the Purchaser in
accordance with the letter delivered to the Seller by the Purchaser attached
hereto as Exhibit A (the "Instruction Letter"). The Seller's records will
accurately reflect the sale of each Mortgage Loan to the Purchaser.

          (b) The ownership of each Mortgage Loan and the related Mortgage Note,
the Mortgage and the contents of the related Mortgage File shall be, upon
satisfaction of subsection 5(a) hereof, vested in the Purchaser and the
ownership of all records and documents with respect to such Mortgage Loan
prepared by or which come into the possession of the Seller shall immediately
vest in the Purchaser and shall be retained and maintained by the Seller at the
will and for the benefit of the Purchaser in a custodial capacity only. The
Seller shall deliver to the Purchaser or its agent in accordance with the
instructions set forth in Exhibit A, simultaneously with the execution and
delivery of this Agreement or prior to the Closing Date, all of the documents
pertaining to each Mortgage Loan previously delivered to the Seller by ABN AMRO
Mortgage Group, Inc. ("AAMGI") pursuant to that certain Mortgage Loan Purchase
Agreement, dated as of July1, 2001, between the Seller, as purchaser, and AAMGI,
as seller.

          (c) The transfer of the Mortgage Loans as described herein shall be
absolute and is intended by the parties to be a sale. In the event that a court
deems the conveyance set forth herein not to constitute a sale, the Seller shall
have granted to the Purchaser a first priority security interest in the Mortgage
Loans and in the proceeds thereof of any kind or nature whatsoever, and in the
proceeds of any related insurance policies, subject to the satisfaction or
waiver of the conditions set forth in Section 11 hereof, and shall take, or
shall cause to have been taken, all steps necessary prior to the Closing Date to
perfect such security interest in the Purchaser.

          SECTION 6. Books and Records.

          On the Closing Date, following the sale of the Mortgage Loans to the
Purchaser, title to each Mortgage and the related Mortgage Note shall be
transferred to the Purchaser or its assignee in accordance with this Agreement.
All rights arising out of the Mortgage Loans after the Cut-Off Date including,
but not limited to, any and all funds received on or in connection with a
Mortgage Loan and due after the Cut-Off Date shall be received and held by the
Seller in a custodial capacity for the benefit of the Purchaser or its assignee
as the owner of the Mortgage Loans in accordance herewith


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and shall be delivered or caused to be delivered by the Seller to the Purchaser
or its assignee on or immediately following the Closing Date. Any funds received
by the Seller or the Purchaser after the Cut-Off Date but due prior to the
Cut-Off Date shall remain the property of the Seller and shall be promptly
remitted to the Seller.

          SECTION 7. Further Actions; Financing Statements.

          (a) In furtherance of the provisions of Section 5(c) hereof, the
Seller agrees to take or cause to be taken such further actions to execute,
deliver and file or cause to be executed, delivered and filed, such further
documents and instruments (including, without limitation, any UCC financing
statements) as the Purchaser may reasonably request, in order to perfect and
maintain the security interest created pursuant to said section and to otherwise
fully effectuate the purposes, terms and conditions of this Agreement, and the
Purchaser shall cooperate in any such action.

          (b) The Seller shall: (i) promptly execute, deliver, and file any
financing statements, amendments, continuation statements, assignments,
certificates and other documents with respect to such security interest as the
Purchaser may reasonably request to perfect or to maintain the perfection of
such security interest, each in form and substance satisfactory to the
Purchaser; and (ii) notify the Purchaser within five (5) days after the
occurrence of any of the following: (A) any change in the Seller's corporate
name or any trade name; (B) any change in the Seller's location of its chief
executive office or principal place of business; and (C) any merger or
consolidation or other change in Seller's identity or material change in its
corporate structure.

          SECTION 8. Representations, Warranties and Agreements of Seller.

          (a) The Seller hereby represents and warrants to the Purchaser as of
the Closing Date (or such other date as is specified in the related
representation or warranty) as follows:

                    (i) The Seller has been duly created and is validly existing
          as a corporation under the laws of the State of Delaware;

                    (ii) The execution and delivery of this Agreement by the
          Seller and its performance of and compliance with the terms of this
          Agreement will not violate the Seller's charter or by-laws or will not
          conflict with or result in a breach of any of the terms or provisions
          of, or constitute a default under, any indenture, mortgage, deed of
          trust, loan agreement or other material agreement or instrument to
          which the Seller is a party or by which the Seller or to which any of
          the property or assets of the Seller is subject;

                    (iii) This Agreement, assuming due authorization, execution
          and delivery by the Purchaser, constitutes a valid and legally binding
          obligation of the Seller, enforceable against the Seller in accordance
          with its terms, subject, as to enforcement, to bankruptcy, insolvency,
          reorganization and other similar laws of general applicability
          relating to or affecting


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          creditors' rights and to general equity principles, regardless of
          whether such enforcement is considered in a proceeding in equity or at
          law;

                    (iv) The Seller is not in default with respect to any order
          or decree of any court or any order, regulation or demand of any
          federal, state, municipal or governmental agency, which default might
          have consequences that would materially and adversely affect the
          condition (financial or other) or operations of the Seller or its
          properties or might have consequences that would affect its
          performance hereunder;

                    (v) No litigation is pending or, to the best of the Seller's
          knowledge, threatened against the Seller which would prohibit its
          entering into this Agreement or performing its obligations under this
          Agreement;

                    (vi) The consummation of the transactions contemplated by
          this Agreement are in the ordinary course of business of the Seller,
          and the transfer, assignment and conveyance of the Mortgage Notes and
          the Mortgages by the Seller pursuant to this Agreement is not subject
          to the bulk transfer or any similar statutory provisions in effect in
          the State of Illinois;

                    (vii) With respect to each Mortgage Loan:

                              (a) that the information set forth in the Mortgage
                    Loan Schedule appearing as an exhibit to this Agreement is
                    true and correct in all material respects at the date or
                    dates respecting which such information is furnished as
                    specified therein;

                              (b) the Seller is the sole owner and holder of
                    each Mortgage Loan free and clear of all liens, pledges,
                    charges or security interests of any nature and has full
                    right and authority, subject to no interest or participation
                    of, or agreement with, any other party, to sell and assign
                    the same;

                              (c) no payment of principal of or interest on or
                    in respect of any Mortgage Loan is 30 days or more past due
                    from the Due Date of such payment;

                              (d) to the best of the Seller's knowledge, as of
                    the date of the transfer of the Mortgage Loans to the
                    Purchaser, there is no valid offset, defense or counterclaim
                    to any Mortgage Note or Mortgage;

                              (e) there is no proceeding pending, or to the best
                    of the Seller's knowledge, threatened for the total or
                    partial condemnation of any of the real property, together
                    with any improvements thereto, securing the indebtedness of
                    the Mortgagor under the related Mortgage Loan (the
                    "Mortgaged Property") and the Mortgaged Property is free of
                    material damage and is in good repair and neither the


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                    Mortgaged Property nor any improvement located on or being
                    part of the Mortgaged Property is in violation of any
                    applicable zoning law or regulation;

                              (f) that each Mortgage Loan complies in all
                    material respects with applicable state or federal laws,
                    regulations and other requirements, pertaining to usury,
                    equal credit opportunity and disclosure laws, and each
                    Mortgage Loan was not usurious at the time of origination;

                              (g) to the best of the Seller's knowledge, all
                    insurance premiums previously due and owing with respect to
                    each Mortgaged Property have been paid and all taxes and
                    governmental assessments previously due and owing, and which
                    may become a lien against the Mortgaged Property, with
                    respect to the Mortgaged Property have been paid;

                              (h) that each Mortgage Note and the related
                    Mortgage are genuine and each is the legal, valid and
                    binding obligation of the maker thereof, enforceable in
                    accordance with its terms except as such enforcement may be
                    limited by bankruptcy, insolvency, reorganization or other
                    similar laws affecting the enforcement of creditors' rights
                    generally and by general equity principles (regardless of
                    whether such enforcement is considered in a proceeding in
                    equity or at law); all parties to the Mortgage Note and the
                    Mortgage had legal capacity to execute the Mortgage Note and
                    the Mortgage; and each Mortgage Note and Mortgage have been
                    duly and properly executed by the Mortgagor;

                              (i) that each Mortgage is a valid and enforceable
                    first lien on the property securing the related Mortgage
                    Note, and that each Mortgage Loan is covered by an ALTA
                    mortgagee title insurance policy or other form of policy or
                    insurance generally acceptable to FNMA or FHLMC, issued by,
                    and is a valid and binding obligation of, a title insurer
                    acceptable to FNMA or FHLMC insuring the originator, its
                    successor and assigns, as to the lien of the Mortgage in the
                    original principal amount of the Mortgage Loan subject only
                    to (a) the lien of current real property taxes and
                    assessments not yet due and payable, (b) covenants,
                    conditions and restrictions, rights of way, easements and
                    other matters of public record as of the date of recording
                    of such Mortgage acceptable to mortgage lending institutions
                    in the area in which the Mortgaged Property is located or
                    specifically referred to in the appraisal performed in
                    connection with the origination of the related Mortgage Loan
                    and (c) such other matters to which like properties are
                    commonly subject which do not individually, or in the
                    aggregate, materially interfere with the benefits of the
                    security intended to be provided by the Mortgage;

                              (j) neither the Seller nor any prior holder of any
                    Mortgage has, except as the Mortgage File may reflect,
                    modified the Mortgage in any material respect; satisfied,
                    cancelled or subordinated such Mortgage in whole or in part;



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                    released such Mortgaged Property in whole or in part from
                    the lien of the Mortgage; or executed any instrument of
                    release, cancellation, modification or satisfaction;

                              (k) that each Mortgaged Property consists of a fee
                    simple estate or condominium form of ownership in real
                    property;

                              (l) the condominium projects that include the
                    condominiums that are the subject of any condominium loan
                    are generally acceptable to FNMA or FHLMC;

                              (m) no foreclosure action is threatened or has
                    been commenced (except for the filing of any notice of
                    default) with respect to the Mortgage Loan; and except for
                    payment delinquencies not in excess of 30 days, to the best
                    of the Seller's knowledge, there is no default, breach,
                    violation or event of acceleration existing under the
                    Mortgage or the related Mortgage Note and no event which,
                    with the passage of time or with notice and the expiration
                    of any grace or cure period, would constitute a default,
                    breach, violation or event of acceleration; and the Seller
                    has not waived any default, breach, violation or event of
                    acceleration;

                              (n) that each Mortgage Loan was originated on FNMA
                    or FHLMC uniform instruments for the state in which the
                    Mortgaged Property is located;

                              (o) that based upon a representation by each
                    Mortgagor at the time of origination or assumption of the
                    applicable Mortgage Loan, all of the Mortgage Loans measured
                    by principal balance were to be secured by owner-occupied
                    residences;

                              (p) that an appraisal of each Mortgaged Property
                    was conducted at the time of origination of the related
                    Mortgage Loan, and that each such appraisal was conducted in
                    accordance with FNMA or FHLMC criteria, on FNMA or FHLMC
                    forms and comparables on at least three properties were
                    obtained;

                              (q) that no Mortgage Loan had a Loan-to-Value
                    Ratio at origination in excess of 95%;

                              (r) the Mortgage Loans were not selected in a
                    manner to adversely affect the interests of the Purchaser
                    and the Seller knows of no conditions which reasonably would
                    cause it to expect any Mortgage Loan to become delinquent or
                    otherwise lose value;

                              (s) each Mortgage Loan was either (A) originated
                    directly by or closed in the name of either: (i) a savings
                    and loan association, savings bank, commercial bank, credit
                    union, insurance company, or similar institution which is


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                    supervised and examined by a federal or state authority or
                    (ii) a mortgagee approved by the Secretary of Housing and
                    Urban Development pursuant to Sections 203 and 211 of the
                    National Housing Act or (B) originated or underwritten by an
                    entity employing underwriting standards consistent with the
                    underwriting standards of an institution as described in
                    subclause (A)(i) or (A)(ii) above;

                              (t) each Mortgage Loan is a "qualified mortgage"
                    within the meaning of Section 860G of the Internal Revenue
                    Code of 1986, without regard to ss.1.860 G-2(f) of the REMIC
                    provisions or any similar rule;

                              (u) each Mortgage Loan that has a Loan-to-Value
                    Ratio at origination in excess of 80% is covered by a
                    primary mortgage insurance policy; and

                              (v) that no Mortgage Loan permits negative
                    amortization or the deferral of accrued interest.

                    It is understood and agreed that the representations and
          warranties set forth in this Section 8 shall survive the sale of the
          Mortgage Loans to the Purchaser and shall inure to the benefit of the
          Purchaser, notwithstanding any restrictive or qualified endorsement on
          any Mortgage Note (or lost note affidavit and indemnity) or assignment
          of Mortgage or the examination of any Mortgage File.

                    Upon discovery by either the Seller, the Purchaser or its
          designees of a breach of any of the foregoing representations or
          warranties of the Seller which materially and adversely affects (1)
          the value of any of the Mortgage Loans actually delivered or (2) the
          interests of the Purchaser therein, the party discovering such breach
          shall give prompt written notice to the other. Within 90 (ninety) days
          of its discovery or its receipt of notice of any such breach of a
          representation or warranty, the Seller shall, with respect to the
          Mortgage Loan(s) to which such breach relates, either (i) cure such
          breach in all material respects, (ii) repurchase such Mortgage Loan or
          Mortgage Loans (or any property acquired in respect thereof) from the
          Purchaser at the Purchase Price, as adjusted for the then current
          principal balance or (iii) within the 90 (ninety)-day period following
          the Closing Date substitute another mortgage loan for such Mortgage
          Loan. Such substitute mortgage loan shall on the date of substitution,
          (a) have a principal balance not in excess of the principal balance of
          the defective Mortgage Loan, (b) be accruing interest at a rate of
          interest at least equal to that of the defective Mortgage Loan, (c)
          have a remaining term to stated maturity not greater than, and not
          more than two years less than, that of the Mortgage Loan so
          substituted, (d) have an original loan-to-value ratio not higher than
          that of the Mortgage Loan so substituted and a current loan-to-value
          ratio not higher than that of the Mortgage Loan so substituted, and
          (e) comply with all the representations and warranties relating to
          Mortgage Loans set forth herein, as of the date of substitution (such
          mortgage loan being referred to herein as a "Qualifying Substitute
          Mortgage Loan"). Except as set forth in Section 12 hereof, it is
          understood and agreed that the obligations of the Seller set forth in
          this Section 8 to cure,


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          substitute for or repurchase a defective Mortgage Loan constitute the
          sole remedies of the Purchaser respecting a breach of the foregoing
          representations and warranties.

                   The Purchaser, upon receipt by it of the full amount of the
          then current principal balance for a Mortgage Loan that is
          repurchased, or upon receipt of the Mortgage File for a Qualifying
          Substitute Mortgage Loan for a Mortgage Loan that is substituted or
          repurchased, shall release or cause to be released and reassign to the
          Seller the related Mortgage File for the Mortgage Loan that is
          substituted and shall execute and deliver such instruments of transfer
          or assignment, in each case without recourse, representation, or
          warranty, as shall be necessary to vest in the Seller or its designee
          or assignee title to any such substituted Mortgage Loan released
          pursuant hereto or Mortgage Loan purchased pursuant hereto, free and
          clear of all security interests, liens and other encumbrances, which
          instruments shall be prepared by the Seller at its expense and shall
          be reasonably acceptable to the Purchaser, and the Purchaser shall
          have no further responsibility with respect to the Mortgage File
          relating to such Mortgage Loan that is substituted.

                   Any cause of action against the Seller or relating to or
          arising out of the breach of any representations and warranties made
          in this Section 8 shall accrue as to any Mortgage Loan upon (i)
          discovery of such breach by the Purchaser or notice thereof by the
          Seller to the Purchaser, (ii) failure by the Seller to cure such
          breach, repurchase such Mortgage Loan or substitute a Qualifying
          Substitute Mortgage Loan as specified above, and (iii) demand upon the
          Seller by the Purchaser for all amounts payable in respect of such
          Mortgage Loan.

          SECTION 9. Representations, Warranties and Agreements of Purchaser.

          (a) The Purchaser hereby represents and warrants to the Seller, as of
the date hereof (or such other date as is specified in the related
representation or warranty) as follows:

                    (i) The Purchaser is a corporation duly formed and validly
          existing under the laws of the State of Delaware;

                    (ii) The execution and delivery of this Agreement by the
          Purchaser and its performance of and compliance with the terms of this
          Agreement will not violate the Purchaser's corporate charter or
          by-laws or will not conflict with or result in a breach of any of the
          terms or provisions of, or constitute a default under, any indenture,
          mortgage, deed of trust, loan agreement or other material agreement or
          instrument to which the Purchaser is a party or by which the Purchaser
          or to which any property or assets of the Purchaser is subject;

                    (iii) This Agreement, assuming due authorization, execution
          and delivery by the Seller, constitutes a valid and legally binding
          obligation of the Purchaser, enforceable against the Purchaser in
          accordance with its terms, subject, as to enforcement, to bankruptcy,
          insolvency, reorganization and other similar laws of general
          applicability relating to or


                                        9

<PAGE>



          affecting creditors' rights and to general equity principles,
          regardless of whether such enforcement is considered in a proceeding
          in equity or at law;

                    (iv) The Purchaser is not in default with respect to any
          order or decree of any court or any order, regulation or demand of any
          federal, state, municipal or governmental agency, which the Purchaser
          default might have consequences that would materially and adversely
          affect the condition (financial or other) or operations of the
          Purchaser or its properties or might have consequences that would
          affect its performance hereunder; and

                    (v) No litigation is pending or, to the best of the
          Purchaser's knowledge, threatened against the Purchaser which would
          prohibit its entering into this Agreement or performing its
          obligations under this Agreement;

          SECTION 10. Purchaser's Conditions to Closing. The obligations of the
Purchaser under this Agreement shall be subject to the satisfaction, on or prior
to the Closing Date, of the following conditions:

          (a) The obligations of the Seller required to be performed by it on or
prior to the Closing Date pursuant to the terms of this Agreement shall have
been duly performed and complied with and all of the representations and
warranties of the Seller under this Agreement shall be true and correct as of
the date hereof and as of the Closing Date, and no event shall have occurred
which, with notice or the passage of time, or both, would constitute a default
under this Agreement, and the Purchaser shall have received a certificate to
that effect signed by an Authorized Officer (as defined below) of the Seller.

          (b) The Purchaser or the Purchaser's document custodian shall have
received, or the Purchaser's attorney shall have received in escrow, all of the
following closing documents, in such forms as are agreed upon and acceptable to
the Purchaser, duly executed by all signatories other than the Purchaser, as
required pursuant to the respective terms thereof:

                    (i) An assignment or assignments of the Mortgage Loans to
          the Purchaser or its designee substantially in the form attached
          hereto as Exhibit B with such changes as are required to adapt the
          assignment to the proper form in the jurisdiction where the related
          Mortgage Property is located, and each original Mortgage Note (or lost
          note affidavit and indemnity), duly endorsed originally or by
          facsimile, without recourse, to                , in each case in
          accordance with the instructions set forth in Exhibit A attached
          hereto, which assignment or assignments and Mortgage Note (or lost
          note affidavit and indemnity) shall be delivered to and held by the
          Purchaser or its agent on behalf of the Purchaser;

                    (ii) The Mortgage Loan Schedule prepared by the Seller dated
          as of the related Closing Date and attached hereto;



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<PAGE>



                    (iii) A certificate signed by an officer, which officer may
          be either a senior vice president, a vice president, an assistant vice
          president or assistant secretary (an "Authorized Officer"), dated as
          of the Closing Date, substantially in the form attached hereto as
          Exhibit C, to the parties hereto, and attached thereto copies of the
          charter and by-laws and a Good Standing Certificate or a memorandum
          setting forth the verbal assurances from the appropriate regulatory
          authorities with respect to the Seller will be immediately
          forthcoming; and

                    (iv) An opinion of Seller's counsel in substantially the
          form attached hereto as Exhibit D.

                    (v) A security release certification, in a form acceptable
          to the Purchaser, executed by the appropriate mortgagee or secured
          party, if any of the Mortgage Loans have at any time been subject to
          any security interest, pledge or hypothecation for the benefit of such
          person.

          (c) The Seller will furnish to the Purchaser such other certificates
of its officers or others and such other documents to evidence fulfillment of
the conditions set forth in this Agreement as the Purchaser and its attorney may
reasonably request.

          SECTION 11. Seller's Conditions to Closing. The obligations of the
Seller under this Agreement shall be subject to the satisfaction, on or prior to
the Closing Date, of the following conditions:

          (a) The obligations of the Purchaser required to be performed by it on
or prior to the Closing Date pursuant to the terms of this Agreement shall have
been duly performed and complied with and all of the representations and
warranties of the Purchaser under this Agreement shall be true and correct as of
the date hereof and as of the Closing Date, and no event shall have occurred
which, with notice or the passage of time, or both, would constitute a default
under this Agreement, and the Seller shall have received a certificate to that
effect signed by an Authorized Officer of the Purchaser;

          (b) The Seller shall have received, or the Seller's attorney shall
have received in escrow, a certificate signed by an Authorized Officer of the
Purchaser dated as of the Closing Date, in the form acceptable to the parties
hereto, and attached thereto the resolutions of the Purchaser authorizing the
transactions contemplated by this Agreement, together with copies of the
Articles of Association and by-laws as of a recent date with respect to the
Purchaser; and

          (c) The Purchaser will furnish to the Seller such other certificates
of its officers or others and such other documents to evidence fulfillment of
the conditions set forth in this Agreement as the Seller and its attorney may
reasonably request.



                                       11

<PAGE>



          SECTION 12. Indemnification.

          (a) The Seller agrees to indemnify and hold harmless the Purchaser
against any and all losses, claims, expenses, damages or liabilities to which
Purchaser may become subject, insofar as such losses, claims, expenses, damages
or liabilities (or actions in respect thereof) arise out of or are based upon
any representation or warranty made by the Seller in Section 8(a)(i) through
Section 8(a)(vi) hereof on which Purchaser has relied, being, or alleged to be,
materially untrue or incorrect. This indemnity will be in addition to any
liability which the Seller may otherwise have.

          (b) The Purchaser agrees to indemnify and hold harmless the Seller
solely in its capacity as seller of the Mortgage Loans against any and all
losses, claims, expenses, damages or liabilities to which the Seller may become
subject, insofar as such losses, claims, expenses, damages or liabilities (or
actions in respect thereof) arise out of or are based upon any representation or
warranty made by the Purchaser in Section 9 hereof on which the Seller has
relied, being, or alleged to be, materially untrue or incorrect (notwithstanding
the Purchaser's lack of knowledge with respect to the substance of any
representation or warranty to which Section 9 applies which is made to the best
of the Purchaser's knowledge). This indemnity will be in addition to any
liability which the Purchaser may otherwise have.

          (c) Promptly after receipt by either the Purchasers or the Seller of
notice of the commencement of any action or proceeding in any way relating to or
arising from this Agreement, such party will notify the other party of the
commencement thereof; but the omission so to notify the party from whom
indemnification is sought (the "Indemnifying Party") will not relieve the
Indemnifying Party from any liability which it may have to the party seeking
indemnification (the "Indemnified Party") except to the extent that the
Indemnifying Party is adversely affected by the lack of notice. In case any such
action is brought against the Indemnified Party, and it notifies the
Indemnifying Party of the commencement thereof, the Indemnifying Party will be
entitled to participate in the defense (with the consent of the Indemnified
Party which shall not be unreasonably withheld) of such action at the
Indemnifying Party's expense.

          SECTION 13. Notices. All demands, notices and communications hereunder
shall be in writing and shall be deemed to have been duly given if mailed, by
registered or certified mail, return receipt requested, or, if by other means,
when received by the other party. Notices to the Seller shall be directed to
Washington Mutual Mortgage Securities Corp., 1201 Third Avenue, Seattle,
Washington 98101, Attention: Legal Services Department; and notices to the
Purchaser shall be directed to ABN AMRO Mortgage Corporation, 135 South LaSalle
Street, Suite 925, Chicago, Illinois 60603, Attention: Maria Fregosi - First
Vice President - ABN AMRO Mortgage Operations, with a copy to ABN AMRO North
America, Inc., 135 South LaSalle Street, Chicago, Illinois 60603, Attention:
Kirk Flores - Associate General Counsel; or such other addresses as may
hereafter be furnished to the other party by like notice.

          SECTION 14. Termination. This Agreement may be terminated (a) by the
mutual consent of the parties hereto, or (b) by the Purchaser if the conditions
to the Purchaser's obligations to


                                       12

<PAGE>



closing set forth under Section 10 hereof are not fulfilled as and when required
to be fulfilled or (c) by the Seller if the Purchaser's obligations under
Section 11 hereof are not fulfilled as and when required. In the event of a
termination pursuant to Section 14(b), the Seller agrees that it will pay the
out-of-pocket fees and expenses of the Purchaser in connection with the
transactions contemplated by this Agreement and in the event of a termination
pursuant to Section 14(c), the Purchaser agrees that it will pay the
out-of-pocket fees and expenses of the Seller in connection with the
transactions contemplated by this Agreement.

          SECTION 15. Representations, Warranties and Agreements to Survive
Delivery. All representations, warranties and agreements contained in this
Agreement, or in certificates of officers of the Seller and the Purchaser
submitted pursuant hereto, shall remain operative and in full force and effect
and shall survive transfer and sale of the Mortgage Loans to the Purchaser.

          SECTION 16. Severability. If any provision of this Agreement shall be
prohibited or invalid under applicable law, the Agreement shall be ineffective
only to such extent, without invalidating the remainder of this Agreement.

          SECTION 17. Counterparts. This Agreement may be executed in any number
of counterparts, each of which shall be an original, but both of which together
shall constitute one and the same agreement.

          SECTION 18. Governing Law. This Agreement shall be deemed to have been
made in the State of New York and shall be interpreted in accordance with the
laws of such state without regard to the principles of conflicts of law of such
state.

          SECTION 19. Further Assurances. The Seller and the Purchaser agree to
execute and deliver such instruments and take such actions as the other party
may, from time to time, reasonably request in order to effectuate the purpose
and to carry out the terms of this Agreement.

          SECTION 20. Successors and Assigns. This Agreement shall be binding
upon and inure to the benefit of and be enforceable by the Seller and the
Purchaser and their permitted successors and assigns. The Seller acknowledges
and agrees that the Purchaser may assign its rights under this Agreement. Any
person into which the Seller may be merged or consolidated (or any person
resulting from any merger or consolidation involving the Seller), or any person
succeeding to the business of the Seller shall be considered the "successor" of
the Seller hereunder. Except as provided in the two preceding sentences, this
Agreement cannot be assigned, pledged or hypothecated by any party hereto
without the written consent of the other party to this Agreement.
Notwithstanding anything to the contrary in this Section 20, the parties hereto
agree that the Purchaser has the right to assign its rights and interest in, to
and under Section 8 hereof.

          SECTION 21. Amendments. No term or provision of this Agreement may be
waived or modified unless such waiver or modification is in writing and signed
by a duly authorized officer of the party against whom such waiver or
modification is sought to be enforced.


                                       13

<PAGE>



          IN WITNESS WHEREOF, the Seller and the Purchaser have caused their
names to be signed hereto by their respective duly authorized officers as of the
date first above written.

                                Washington Mutual Mortgage Securities Corp.,
                                as Seller


                                By:      /s/ Michael Parker
                                   ------------------------------------------
                                Name:    Michael Parker
                                Title:   President















                                                Mortgage Loan Purchase Agreement



                                       14

<PAGE>



                                           ABN AMRO Mortgage Corporation,
                                           as Purchaser


                                           By:      /s/ Daniel J.  Fischer
                                              -----------------------------
                                           Name:    Daniel J. Fischer
                                           Title:   Vice President











                                                Mortgage Loan Purchase Agreement



                                       15

<PAGE>



                                   SCHEDULE 1

                             MORTGAGE LOAN SCHEDULE


         A listing of specific mortgage loans is available upon request




                                       16

<PAGE>



                                   SCHEDULE 2

                       MORTGAGE LOAN SCHEDULE INFORMATION

          Each Mortgage Loan shall be identified by at least the following
details, among others, relating to each Mortgage Loan:

          (i)       the loan number of the Mortgage Loan and name of the related
                    Mortgagor;

          (ii)      the street address of the Mortgaged Property including city,
                    state and zip code;

          (iii)     the mortgage interest rate as of the Cut-Off Date;

          (iv)      the original term and maturity date of the related Mortgage
                    Note;

          (v)       the original principal balance;

          (vi)      the first payment date;

          (vii)     the monthly payment in effect as of the Cut-Off Date;

          (viii)    the date of the last paid installment of interest;

          (ix)      the unpaid principal balance as of the close of business on
                    the Cut-Off Date;

          (x)       the loan-to-value ratio at origination;

          (xi)      the type of property and the Original Value (as defined in
                    the Pooling and Servicing Agreement) of the Mortgaged
                    Property;

          (xii)     whether a primary mortgage insurance policy is in effect as
                    of the Cut-Off Date;

          (xiii)    the nature of occupancy at origination;

          (xiv)     the servicing fee;

          (xv)      the county in which the Mortgaged Property is located, if
                    available; and

          (xvi)     the Closing Date.


                                       17

<PAGE>



                                   SCHEDULE 3

                            MORTGAGE FILE INFORMATION


          Each Mortgage File shall include at least the following documents,
among others, with respect to each Mortgage Loan transferred and assigned from
the Seller to the Purchaser, or its agent:

          (i)       the original Mortgage Note (or, if the original Mortgage
                    Note has been lost or destroyed, a lost note affidavit and
                    indemnity) bearing all intervening endorsements endorsed,
                    "Pay to the order of ______________, without recourse" and
                    signed in the name of the mortgagee at the request of the
                    Seller by an Authorized Officer showing an unbroken chain of
                    title from the originator thereof to the person endorsing;

          (ii)      (a) the original Mortgage with evidence of recording
                    thereon, and if the Mortgage was executed pursuant to a
                    power of attorney, a certified true copy of the power of
                    attorney certified by the recorder's office, with evidence
                    of recording thereon, or certified by a title insurance
                    company or escrow company to be a true copy thereof;
                    provided, that if such original Mortgage or power of
                    attorney cannot be delivered with evidence of recording
                    thereon on or prior to the Closing Date because of a delay
                    caused by the public recording office where such original
                    Mortgage has been delivered for recordation or because such
                    original Mortgage has been lost, the Seller shall deliver or
                    cause to be delivered to the Purchaser (with a copy to the
                    Trustee (as defined in the Pooling and Servicing Agreement))
                    a true and correct copy of such Mortgage, together with (1)
                    in the case of a delay caused by the public recording
                    office, a certificate signed by an Authorized Officer of the
                    Seller stating that such original Mortgage has been
                    dispatched to the appropriate public recording official for
                    recordation or (2) in the case of an original Mortgage that
                    has been lost, a certificate by the appropriate county
                    recording office where such Mortgage is recorded or from a
                    title insurance company or escrow company indicating that
                    such original was lost and the copy of the original mortgage
                    is a true and correct copy;

                    (b) the original assignment to "State Street Bank and Trust
                    Company, as trustee/custodian," which assignment shall be in
                    form and substance acceptable for recording, or a copy
                    certified by the Seller as a true and correct copy of the
                    original assignment which has been sent for recordation.
                    Subject to the foregoing, such assignments may, if permitted
                    by law, be by blanket assignments for Mortgage Loans
                    covering Mortgaged Properties situated within the same
                    county. If the assignment is in blanket form, a copy of the
                    assignment shall be included in the related individual
                    Mortgage File;



<PAGE>



          (iii)     the originals of any and all instruments that modify the
                    terms and conditions of the Mortgage Note, including but not
                    limited to modification, consolidation, extension and
                    assumption agreements including any adjustable rate mortgage
                    (ARM) rider, if any;

          (iv)      the originals of all required intervening assignments, if
                    any, with evidence of recording thereon, and if such
                    assignment was executed pursuant to a power of attorney, a
                    certified true copy of the power of attorney certified by
                    the recorder's office, with evidence of recording thereon,
                    or certified by a title insurance company or escrow company
                    to be a true copy thereof; provided, that if such original
                    -------- assignment or power of attorney cannot be delivered
                    with evidence of recording thereon on or prior to the
                    Closing Date because of a delay caused by the public
                    recording office where such original assignment has been
                    delivered for recordation or because such original
                    assignment has been lost, the Seller shall deliver or cause
                    to be delivered to the Purchaser (with a copy to the Trustee
                    (as defined in the Pooling and Servicing Agreement)) a true
                    and correct copy of such assignment, together with (a) in
                    the case of a delay caused by the public recording office, a
                    certificate signed by an Authorized Officer of the Seller
                    stating that such original assignment has been dispatched to
                    the appropriate public recording official for recordation or
                    (b) in the case of an original assignment that has been
                    lost, a certificate by the appropriate county recording
                    office where such assignment is recorded or from a title
                    insurance company or escrow company indicating that such
                    original was lost and the copy of the original assignment is
                    a true and correct copy;

          (v)       the original mortgagee policy of title insurance (including,
                    if applicable, the endorsement relating to the negative
                    amortization of the Mortgage Loans) or in the event such
                    original title policy is unavailable, any one of an original
                    title binder, an original preliminary title report or an
                    original title commitment or a copy thereof certified by the
                    title company with the original policy of title insurance to
                    follow within 180 days of the Closing Date;

          (vi)      the mortgage insurance certificate;

          (vii)     hazard insurance certificates and copies of the Hazard
                    Insurance Policy and, if applicable, flood insurance policy;
                    and

          (viii)    any and all other documents, opinions and certificates
                    executed and/or delivered by the related Mortgagor and/or
                    its counsel in connection with the origination of such
                    Mortgage Loan, which may include truth-in-lending statements
                    and other legal statements, and appraisal and a survey.


                                        2

<PAGE>



                                    EXHIBIT A

                               INSTRUCTION LETTER

                          ABN AMRO Mortgage Corporation
                       135 South LaSalle Street, Suite 925
                             Chicago, Illinois 60602


                                                               ________ __, 2001


Washington Mutual Mortgage Securities Corp.
1201 Third Avenue, WMT 17
Seattle, Washington 98101

Dear Ladies and Gentlemen:

          Pursuant to the Mortgage Loan Purchase Agreement dated as of July 27,
2001 (the "Purchase Agreement") between you and us, we have agreed to purchase
from you certain Mortgage Loans. All capitalized terms used herein and not
otherwise defined shall have the meanings set forth in the Purchase Agreement.

          In order to facilitate these transactions, and for the purpose of
convenience only, we hereby authorize and direct you to:

<TABLE>
<CAPTION>
Action                                                   Due Date
<S>                                                      <C>
1.  Endorse mortgage notes (or lost note affidavits      on or before the Closing Date
    and indemnities) to:
    "Pay to the order of State Street Bank and Trust
    Company, As trustee/custodian, for the benefit of
    the Certificateholders of ABN AMRO Mortgage
    Corporation Series 2001-4, without recourse"

2.  Assign mortgages to be recorded                      on or before the Closing Date
    to State Street Bank and Trust Company, as
    Trustee:

3.  Deliver or caused to be delivered to the Purchaser   two business days after funding
    or its agent a Mortgage File for each Mortgage
    Loan



<PAGE>



4.  Provide lost mortgage note affidavits, certified     on or before the Closing Date
    copies of all missing mortgages, and certified
    recorded copies of missing intervening
    assignments

5.  Mortgage Loan Schedule generated by Seller and       one day prior to funding
    agreed to by Purchaser
</TABLE>

                                      Sincerely,

                                      ABN AMRO Mortgage Corporation


                                      By:
                                         ---------------------------------
                                      Name:
                                           -------------------------------
                                      Title:
                                            ------------------------------




                                        2

<PAGE>



                                    EXHIBIT B


                               FORM OF ASSIGNMENT


          Washington Mutual Mortgage Securities Corp., a Delaware corporation
(the "Seller"), in exchange for $__________ in hand paid and other good and
valuable consideration, hereby grants, bargains, sells, assigns, transfers,
conveys, and sets over to ABN AMRO Mortgage Corporation, a Delaware corporation
(the "Purchaser"), all of the Seller's right, title, and interest in, to, and
under the mortgage loans listed on Schedule 1 attached hereto, the mortgage
notes evidencing or relating to such mortgage loans, all mortgages, trust deeds,
title insurance policies, property insurance policies, chattel paper, loan
guaranties, loan accounts, surveys, instruments, certificates, and other
documents whatsoever evidencing or relating to such mortgage notes and mortgage
loans, and all books, ledgers, books of account, records, writings, data bases,
information, and computer software (and all documentation therefor or relating
thereto, and all licenses relating to or covering such computer software and/or
documentation), and all other property, rights, title, and interests whatsoever
relating to, used, or useful in connection with, or evidencing, embodying,
incorporating, or referring to, any of the foregoing (the "Mortgages"). The
Seller warrants to the Purchaser that the Seller is the owner of the Mortgages,
subject to no liens, claims, or encumbrances.




<PAGE>



Dated: _________, 2001             Washington Mutual Mortgage Securities Corp.


                                   By:
                                      ------------------------------------
                                      Name:
                                           -------------------------------
                                      Title:
                                            ------------------------------




                                        2

<PAGE>



ACKNOWLEDGED ON __________ __, 2001

ABN AMRO Mortgage Corporation


By:
   -----------------------------------
   Name:
        ------------------------------
   Title:
         -----------------------------



                                        3

<PAGE>



STATE OF    ____________ )
                         )
COUNTY OF   ____________ )


          I, ______________, a Notary Public in and for the said County and
State, do hereby certify that ____________, personally known to me to be the
same person whose name is subscribed to the foregoing instrument as
_______________ of __________________, appeared before me this day in person
and, being first sworn, acknowledged that he signed and delivered the said
instrument as his own free and voluntary act, and as the free and voluntary act
of said corporation as the ___________ of ____________, a ____________, for the
uses and purposes therein set forth and that he was duly authorized to execute
the said instrument by the __________________ of said ____________________.

          Given under my hand and seal, this ____ day of ____________, 2001.


                                        ----------------------------------
                                        Notary Public

                                        My commission expires:
                                                              -----------------



                                        4

<PAGE>



                                    EXHIBIT C

                          FORM OF OFFICER'S CERTIFICATE

                   Washington Mutual Mortgage Securities Corp.

          I, ____________________, do hereby certify pursuant to Section 10(a)
and (b)(iii) of the Purchase Agreement (as hereinafter defined) that I am the
duly elected ____________________ of Washington Mutual Mortgage Securities Corp.
("WAMU" ), a Delaware corporation, and further certify as follows:

          1. Attached hereto as Exhibit "A" is a true and correct copy of the
articles of incorporation of WAMU. There has been no amendment or other document
filed affecting the charter as of the date of this certification of WAMU, and no
such amendment has been authorized.

          2. Attached hereto as Exhibit "B" is a true and correct copy of the
by-laws of WAMU as in full force and effect as of the date of this
certification.

          3. No proceedings looking toward merger, consolidation, liquidation,
or dissolution of WAMU are pending or contemplated.

          4. Each person who, as an officer or representative of WAMU, signed,
or will sign (a) the Purchase Agreement, and (b) any other document delivered
pursuant thereto or on the date hereof in connection with the Mortgage Loan
Purchase Agreement, dated as of July 27, 2001, between WAMU, as seller, and ABN
AMRO Mortgage Corporation, as Purchaser (the "Purchase Agreement") was, at the
respective times of such signing and delivery, and is as of the date hereof duly
elected or appointed, qualified and acting as such officer or representative,
and the signatures of such persons appearing on such documents are their genuine
signatures.

          5. Attached hereto as Exhibit "C" is a true, complete and correct copy
of the Resolutions of WAMU's Board of Directors, which were duly adopted as of
_____ __, ____, and such Resolutions have not been amended, altered or repealed,
and remain in full force and effect without modification on the date hereof.

          6. Attached hereto as Exhibit "D" is a Good Standing Certificate
issued by the Office of the Secretary of State of Delaware as of __________,
____. A current Good Standing Certificate has been requested from the Office of
the Secretary of State of _________ and will be supplied when it is received.

          7. WAMU has performed all obligations and satisfied all conditions on
its part to be performed or satisfied under the Purchase Agreement on or prior
to the Closing Date and all of the representations and warranties of the Seller
under the Purchase Agreement are true and correct as of the date hereof and as
of the Closing Date, and no event has occurred which, with notice or passage of
time, or both, would constitute a default under the Purchase Agreement.




<PAGE>



All capitalized terms used herein and not otherwise defined shall have the
meanings set forth in the Purchase Agreement.

IN WITNESS WHEREOF, I have hereunto signed my name.

Date:__________ __, ____

                                 Washington Mutual Mortgage Securities Corp.



                                 By:
                                    -------------------------------------
                                 Name:
                                      -----------------------------------
                                 Title:
                                       ----------------------------------




                                        2

<PAGE>



          I, ____________________, __________________________ of Washington
Mutual Mortgage Securities Corp., a Delaware corporation, hereby certify that
____________________ is the duly elected, qualified and acting
____________________ of Washington Mutual Mortgage Securities Corp. and that the
signature appearing on the preceding page is his genuine signature. IN WITNESS
WHEREOF, I have hereunto signed my name. Date: __________ __, ____

                                    Washington Mutual Mortgage Securities Corp.



                                    By:
                                       -------------------------------------
                                    Name:
                                         -----------------------------------
                                    Title:
                                          ----------------------------------



                                        3

<PAGE>



                    [OPINION TO BE REVISED IN ACCORDANCE WITH
                    GENERAL COUNSEL'S FORM OF OPINION LETTER]


                                    Exhibit D

                      [OPINION OF SELLER'S IN-HOUSE COUNSEL
                         PURSUANT TO SECTION 10(B)(IV)]
                                -----------------



                               __________ __, 2001



ABN AMRO Mortgage Corporation
135 S. LaSalle Street, Suite 925
Chicago, Illinois 60603

          Re: ABN AMRO Mortgage Corporation Purchase of Mortgage Loans

Ladies and Gentlemen:

          As General Counsel to Washington Mutual Mortgage Securities Corp., a
Delaware Corporation ("Seller"), I and attorneys working under my supervision
have acted as counsel to Seller in connection with the sale of Mortgage Loans by
Seller to ABN AMRO Mortgage Corporation (the "Purchaser") pursuant to a Mortgage
Loan Purchase Agreement, dated as of July 27, 2001 (the "Purchase Agreement"),
between the Purchaser and Seller. This opinion is being delivered to the
Purchaser pursuant to Section 10(b)(iv) of the Purchase Agreement. All
capitalized terms not otherwise defined herein have the meanings given them in
the Purchase Agreement.

          In rendering the opinions set forth below, we have examined and relied
upo originals or copies, certified or otherwise identified to our satisfaction,
of the charter and by-laws of Seller, the Purchase Agreement and such corporate
records, agreements or other instruments of Seller, and such certificates,
records and other documents, agreements and instruments, including, among other
things, certain documents delivered on the Closing Date, as we have deemed
necessary and proper as the basis for our opinions. In connection with such
examination, we have assumed the genuineness of all signatures, the authenticity
of all documents, agreements and instruments submitted to us as originals, the
conformity to original documents, agreements and instruments of all documents,
agreements and instruments submitted to us as copies or specimens, the
authenticity of the originals of such documents, agreements and instruments
submitted to us as copies or specimens, the conformity to executed original
documents of all documents submitted to us in draft and the accuracy of the
matters set forth in the documents we reviewed. We have also assumed that all
documents, agreements and instruments have been duly authorized, executed and
delivered by all parties thereto. As to any facts material to such opinions that
we did not independently establish



<PAGE>


ABN AMRO Mortgage Corporation
__________ __, 200_
Page 2



or verify, we have relied upon statements and representations of officers and
other representatives of Seller as we have deemed necessary and proper as the
basis for our opinions, including, among other things, the representations and
warranties of Seller in the Purchase Agreement.

          Based upon the foregoing, I am of the opinion that:

          1. Seller is a corporation, duly organized, validly existing and in
good standing under the laws of Delaware and either is not required to be
qualified to do business under the laws of any states where such qualification
is necessary to transact the business contemplated by the Purchase Agreement, or
is qualified to do business under the laws of any states where such
qualification is necessary to transact the business contemplated by the Purchase
Agreement, and Seller is duly authorized and has full corporate power and
authority to transact the business contemplated by the Purchase Agreement.

          2. The Purchase Agreement has been duly authorized, executed and
delivered by Seller and is a legal, valid and binding obligation of and is
enforceable against Seller in accordance with its terms, except that the
enforceability thereof may be subject to (A) bankruptcy, insolvency,
receivership, conservatorship, reorganization, moratorium or other laws, now or
hereafter in effect, relating to creditors' rights generally, (B) general
principles of equity (regardless of whether enforcement is sought in a
proceeding in equity or at law) and (C) limitations of public policy under
applicable securities laws as to rights of indemnity and contribution under the
Purchase Agreement.

          3. No consent, approval, authorization or order of any court or
supervisory, regulatory, administrative or governmental agency or body is
required for the execution, delivery and performance by Seller of or compliance
by Seller with the Purchase Agreement, the sale of the Mortgage Loans or the
consummation of the transactions contemplated by the Purchase Agreement.

          4. Neither the execution and delivery by Seller of the Purchase
Agreement, nor the consummation by Seller of the transactions contemplated
therein, nor the compliance by Seller with the provisions thereof, will conflict
with or result in a breach of any of the terms, conditions or provisions of
Seller's charter or by-laws or board or shareholder's resolutions, or any
agreement or instrument to which Seller is now a party or by which it is bound,
or constitute a default or result in an acceleration under any of the foregoing,
or result in the violation of any law, rule, regulation, order, judgment or
decree to which Seller or its property is subject, which, in any of the above
cases, would materially and adversely affect Seller's ability to perform its
obligations under the Purchase Agreement.

          5. There is not an action, suit, proceeding or investigation pending
or, to the best of my knowledge, threatened against Seller which, either in any
one instance or in the aggregate, would




<PAGE>


ABN AMRO Mortgage Corporation
__________ __, 200_
Page 3

draw into question the validity of the Purchase Agreement or the Mortgage Loans
or of any action taken or to be taken in connection with the obligations of
Seller contemplated therein, or which would be likely to materially impair the
ability of Seller to perform under the terms of the Purchase Agreement.

          The Opinions expressed herein are limited to matters of federal and
________________ law and do not purport to cover any matters as to which laws of
any other jurisdiction are applicable. Except as expressly provided herein, this
opinion is being furnished to you solely for your benefit in connection with the
purchase of the Mortgage Loans, and it is not to be used, circulated, quoted or
otherwise referred to for any purpose without my express written consent.


                                    Sincerely,


                                    Washington Mutual Mortgage Securities Corp.



                                    By:
                                       ---------------------------------------
                                    Title: General Counsel