OMNIBUS AMENDMENT AGREEMENT NO. 2

     Omnibus Amendment Agreement No. 2 dated March 27, 2002 among the entities
set forth on the signatures pages hereof (this "Agreement").

W I T N E S S E T H

  T H A T:

     WHEREAS, pursuant to Section 6.04 of that certain Guaranty dated as of
December 21, 2001 between TPG Partners III, L.P., a Delaware limited partnership
("TPG Partners III"), TPG GenPar III, L.P., a Delaware limited partnership and
Citicorp USA, Inc., as administrative agent (the "Administrative Agent"), as
amended by the Omnibus Amendment Agreement dated as of January 25, 2002, among
the parties thereto (the "TPG Guaranty"), the TPG Guaranty is being amended
contemporaneously herewith pursuant to Amendment No. 1 dated March [ ], 2002
among the parties thereto (the "Guaranty Amendment No. 1") so that TPG Parallel
III, L.P., TPG Investors III, L.P., FOF Partners III, L.P., FOF Partners III-B,
L.P., T3 Partners, L.P., T3 Parallel, L.P., T3 Investors, L.P., T3 Partners II,
L.P. and T3 Parallel II, L.P., each a Delaware limited partnership (the
"Delaware TPG Guarantors"), TPG Dutch Parallel III, C.V. and T3 Dutch Parallel,
C.V., each a commanditaire vennootschap (limited partnership) formed under the
laws of the Netherlands (together with the Delaware TPG Guarantors, the "New TPG
Guarantors"), may be added to the TPG Guaranty as several, but not joint,
"Guarantors" thereunder;

     WHEREAS, each of the New TPG Guarantors is willing to be so added to the
TPG Guaranty provided that each also becomes a party to the Reimbursement
Agreement by and among MEMC Electronic Materials, Inc. ("MEMC"), TCW/Crescent
Mezzanine Partners III, L.P., TCW/Crescent Mezzanine Trust III, TCW/Crescent
Mezzanine III Netherlands, L.P. (collectively, "TCW"), Green Equity Investors
III, L.P., Green Equity Investors Side III (collectively, "LGP"), TPG Partners
III and Citicorp USA, Inc., as collateral agent (the "Collateral Agent") (as
amended from time to time, the "Reimbursement Agreement"); the Intercreditor
Agreement by and among the Administrative Agent, the Collateral Agent, TPG
Partners III, TCW and LGP (as amended from time to time, the "Pari Passu
Intercreditor Agreement") and the Intercreditor Agreement by and among TPG
Partners III, TPG Wafer Management, L.L.C., TPG Wafer Partners, L.L.C., TCW and
LGP (as amended from time to time, the "Intercreditor Agreement"), each dated as
of December 21, 2001 (collectively, the "MEMC Documents"); and

     WHEREAS, the parties to the MEMC Documents wish to effect the amendments
provided in this Agreement.

     NOW, THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, and intending legally to be bound, the parties hereto hereby agree
as follows:

 1. The Reimbursement Agreement is hereby amended pursuant to Section 8.09
    thereto to include the New TPG Guarantors within the definitions of "Fund
    Guarantors," "TPG Guarantor" and "TPG Percentage."
 2. The Pari Passu Intercreditor Agreement is hereby amended pursuant to Article
    VI thereto to include the New TPG Guarantors within the definitions of "Fund
    Guarantors" and "TPG Percentage" in Schedule I thereto.
 3. The Intercreditor Agreement is hereby amended pursuant to Section 11 thereto
    to include the New TPG Guarantors within the definitions of "Fund
    Guarantors," "TPG" and "TPG Guarantor."
 4. For the avoidance of doubt, and by reason of Section 1 hereof, MEMC and the
    Collateral Agent hereby confirm that the New TPG Guarantors are included
    within the terms "TPG Guarantor," "Fund Guarantors" and "Secured Parties" in
    the Amended and Restated Security Agreement dated as of December 21, 2001,
    among MEMC, certain subsidiaries of MEMC and the Collateral Agent.
 5. Except as specifically amended hereby, the MEMC Documents shall remain in
    full force and effect and nothing herein shall alter, reduce or otherwise
    modify the obligations of any party under the MEMC Documents.
 6. This Agreement may be executed in two or more counterparts, each of which
    shall constitute an original but all of which when taken together shall
    constitute a single contract. Delivery of an executed signature page to this
    Agreement by facsimile transmission shall be effective as delivery of a
    manually executed counterpart hereof. This Agreement shall be binding upon
    and inure to the benefit of the parties hereto and their respective
    successors and assigns.
    THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE
    LAWS OF THE STATE OF NEW YORK.
 7. In the event any one or more of the provisions contained in this Agreement
    should be held invalid, illegal or unenforceable in any respect, the
    validity, legality and enforceability of the remaining provisions contained
    herein shall not in any way be affected or impaired thereby (it being
    understood that the invalidity of a particular provision in a particular
    jurisdiction shall not in and of itself affect the validity of such
    provision in any other jurisdiction). The parties hereto shall endeavor in
    good-faith negotiations to replace the invalid, illegal or unenforceable
    provisions with valid provisions the economic effect of which comes as close
    as possible to that of the invalid, illegal or unenforceable provisions.

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed on the day and year first written above.

MEMC ELECTRONIC MATERIALS, INC.

By: /s/ James M. Stolze
Name: James M. Stolze
Title: Executive Vice President,
Chief Financial Officer

By: /s/ Kenneth L. Young

Name: Kenneth L. Young
Title: Treasurer

CITICORP USA, INC.,
as Administrative and Collateral Agent

By: /s/ Edward T. Crook
Name: Edward T. Crook
Title: Managing Director

TPG PARTNERS III, L.P.

By: TPG GenPar III, L.P., its general partner
By: TPG Advisors III, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

TPG PARALLEL III, L.P.

By: TPG GenPar III, L.P., its general partner
By: TPG Advisors III, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

TPG INVESTORS III, L.P.

By: TPG GenPar III, L.P., its general partner
By: TPG Advisors III, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

FOF PARTNERS III, L.P.

By: TPG GenPar III, L.P., its general partner
By: TPG Advisors III, Inc., its general partner

By: /s/ Richad A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

FOF PARTNERS III-B, L.P.

By: TPG GenPar III, L.P., its general partner
By: TPG Advisors III, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

TPG DUTCH PARALLEL III, C.V

By: TPG GenPar Dutch, L.L.C., its general partner
By: TPG GenPar III, L.P., its sole member
By: TPG Advisors III, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

T3 PARTNERS, L.P.

By: T3 GenPar, L.P., its general partner
By: T3 Advisors, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

T3 PARALLEL, L.P.

By: T3GenPar, L.P., its general partner
By: T3 Advisors, Inc., its general partner

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President:

TCW/CRESCENT MEZZANINE PARTNERS III, L.P.,
TCW/CRESCENT MEZZANINE TRUST III and
TCW/CRESCENT MEZZANINE III NETHERLANDS, L.P.

By: TCW/Crescent Mezzanine Management III, L.L.C., as its
Investment Manager

By: TCW Asset Management Company, as
Its Sub-Advisor

By: /s/ Jean-Marc Chapus
Name: Jean Marc Chapus
Title: Managing Director

By: /s/ James C. Shevlet, Jr.
Name: James C. Shevlet, Jr.
Title: Senior Vice President

GREEN EQUITY INVESTORS III, L.P

By: GEI Capital III, LLC, as its General Partner

By: /s/ John Danhakl
Name: John Danhakl
Title:

GREEN EQUITY INVESTORS SIDE III, L.P.

By: GEI Capital III, LLC, as its General Partner

By: /s/ John Danhakl
Name: John Danhakl
Title:

With respect to Section 4 only:

GEI CAPITAL III, LLC

By: /s/ John Danhakl
Name: John Danhakl
Title:

TPG WAFER MANAGEMENT, L.L.C.

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President

TPG WAFER PARTNERS, L.L.C.

By: /s/ Richard A. Ekleberry
Name: Richard A. Ekleberry
Title: Vice President