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                                                                    EXHIBIT 4.21



                      SECOND AMENDMENT TO WARRANT AGREEMENT


         THIS SECOND AMENDMENT TO WARRANT AGREEMENT (this "AMENDMENT") is made
as of the 9th day of April, 1997, by and among The Cerplex Group, Inc., a
Delaware corporation (the "COMPANY") and each of the holders of warrants listed
on Schedule A hereto, each of which is herein referred to as a "HOLDER" and
collectively as the "HOLDERS."

                                    RECITALS:

         A. The Company and the Holders entered into a Warrant Agreement dated
as of November 19, 1993, as amended by a First Amendment to Warrant Agreement
dated as of April 15, 1996 (as in effect prior to the effectiveness of this
Amendment, the "EXISTING WARRANT AGREEMENT").

         B. The Holders are the holders of all of the Warrants (as such term is
defined in the Existing Warrant Agreement) outstanding as of the date hereof.

         C. The Company has requested that the Existing Warrant Agreement be
amended, as more particularly provided herein, and the Holders have agreed to
amend the Existing Warrant Agreement as set forth herein.

                                   AGREEMENT:

         NOW THEREFORE, for valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties hereto agree as follows:

         SECTION 1. DEFINED TERMS.

         As used in this Amendment, the following terms have the respective
meanings specified below:

         "AMENDMENT, THIS" -- means this First Amendment to Warrant Agreement.

         "COMPANY" -- the introductory sentence.

         "EXISTING WARRANT AGREEMENT" -- Recital A.

         "HOLDERS" -- the introductory sentence.

         SECTION 2. AMENDMENT TO EXISTING WARRANT AGREEMENT; AFFIRMATION.

         2.1      AMENDMENT TO THE EXISTING WARRANT AGREEMENT.

         Section 4.1(d)(ii) of the Existing Warrant Agreement is hereby amended
by:

                  (a) deleting the word "and" at the end of clause (D);


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                  (b) deleting the period and the end of clause (E) and
         substituting "; and" in lieu thereof; and

                  (c) adding the following clause (F) immediately following
         clause (E):

                      (F) warrants, not exceeding eight hundred seventy-five
                  thousand (875,000) in the aggregate, and shares of Common
                  Stock issuable upon the exercise of such warrants, issued on
                  or prior to April 9, 1997 to any then holder of the Wells
                  Fargo Credit Agreement Debt (as such term is defined in the
                  Note Purchase Agreement).

         2.2      AFFIRMATION OF OBLIGATIONS.

         The Company hereby acknowledges and affirms all of its obligations
under the terms of the Existing Warrant Agreement, as amended hereby.

         SECTION 3. MISCELLANEOUS.

         3.1      GOVERNING LAW.

         This Amendment shall be governed by, and construed and enforced in
accordance with, internal New York law.

         3.2      DUPLICATE ORIGINALS.

         Two or more duplicate originals of this Amendment may be signed by the
parties, each of which shall be an original but all of which together shall
constitute one and the same instrument. This Amendment may be executed in one or
more counterparts and shall be effective when at least one counterpart shall
have been executed by each party hereto, and each set of counterparts which,
collectively, show execution by each party hereto shall constitute one duplicate
original.

         3.3      EFFECT OF THIS AMENDMENT.

         Except as specifically provided in this Amendment, no terms or
provisions of the Existing Warrant Agreement have been modified or changed by
this Amendment and the terms and provisions of the Existing Warrant Agreement,
as amended hereby, shall continue in full force and effect. This Amendment and
the amendments contained herein shall have and be in effect on and after the
date hereof.

         3.4      SECTION HEADINGS.

         The titles of the sections hereof appear as a matter of convenience
only, do not constitute a part of this Amendment and shall not affect the
construction hereof.

      [Remainder of Page Intentionally Blank. Next Page is Signature Page.]


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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed on their behalf by a duly authorized officer or agent thereof, as the
case may be, as of the date first above written.

                                      THE CERPLEX GROUP, INC.



                                      By________________________________
                                        Name:
                                        Title:


                                      THE NORTHWESTERN MUTUAL LIFE
                                      INSURANCE COMPANY



                                      By________________________________
                                        Name:
                                        Title:


                                      JOHN HANCOCK MUTUAL LIFE
                                      INSURANCE COMPANY



                                      By________________________________
                                        Name:
                                        Title:


                                      NORTH ATLANTIC SMALLER COMPANIES
                                      INVESTMENT TRUST PLC



                                      By________________________________
                                        Name:
                                        Title:


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                                   SCHEDULE A

                               Schedule of Holders


The Northwestern Mutual Life Insurance Company
720 East Wisconsin Avenue
Milwaukee, Wisconsin 53202

John Hancock Mutual Life Insurance Company
John Hancock Place
200 Clarendon Street
Boston, Massachusetts 02117

North Atlantic Smaller Companies Trust PLC
c/o J.O. Hambro & Co., Ltd.
10 Park Place
London, England SW1A1LP


                                  Schedule A-1