Conformed Copy











                                    GUARANTEE

                            BY WASTE MANAGEMENT, INC.
                  (formerly known as USA Waste Services, Inc.)

                             in Favor of the Holders
                          of Certain Debt Securities of

                         WASTE MANAGEMENT HOLDINGS, INC.
                   (formerly known as Waste Management, Inc.)

                     LIQUID YIELD OPTION(TM) NOTES DUE 2012
                          (Zero Coupon - Subordinated)







                   GUARANTEE, dated as of July 16, 1998, made by Waste
Management, Inc. (formerly known as USA Waste Services, Inc.), a Delaware
corporation (the "Guarantor"), in favor of the holders of the Liquid Yield
Option(TM) Notes due 2012 (Zero Coupon - Subordinated) (the "Debt Securities")
of Waste Management Holdings, Inc. (formerly known as Waste Management, Inc.), a
Delaware corporation (the "Issuer").


                              W I T N E S S E T H:

                   SECTION 1. Guarantee. The Guarantor hereby unconditionally
guarantees the punctual payment when due, whether at stated maturity, by
acceleration or otherwise, of the principal of, premium, if any, and interest on
the Debt Securities (the "Obligations"), according to the terms of the Debt
Securities and as more fully described in the Indenture (as amended, modified or
otherwise supplemented from time to time, the "Indenture") dated as of November
1, 1988, between the Issuer and Harris Trust and Savings Bank, as trustee (the
"Trustee").

                   SECTION 2. Guarantee Absolute. The Guarantor guarantees that
the Obligations will be paid strictly in accordance with the terms of the
Indenture, regardless of any law, regulation or order now or hereafter in effect
in any jurisdiction affecting any of such terms or the rights of holders of the
Debt Securities with respect thereto. The liability of the Guarantor under this
Guarantee shall be absolute and unconditional irrespective of:

                   (i) any lack of validity or enforceability of the Indenture
          or any other agreement or instrument relating thereto;

                   (ii) any change in the time, manner or place of payment of,
          or in any other term of, all or any of the Obligations, or any other
          amendment or waiver of or any consent to departure from the Indenture;

                   (iii) any exchange, release or non-perfection of any
          collateral, or any release or amendment or waiver of or consent to
          departure from any other guaranty, for all or any of the Obligations;
          or

                   (iv) any other circumstance which might otherwise constitute
          a defense available to, or a discharge of, the Issuer, or a guarantor.

                   SECTION 3. Subordination. The Guarantor covenants and agrees
that its obligation to make payments of the Obligations hereunder constitutes an
unsecured obligation of the Guarantor ranking (a) subordinate and junior in
right of payment to all "Senior Indebtedness" (as such term is defined in each
of (i) the Indenture, dated as of February 1, 1997, between the Guarantor and
Texas Commerce Bank National Association, (ii) the Indenture, dated as of June
5, 1996, between United Waste Systems, Inc. ("United") and Bankers Trust
Company, as supplemented by the First Supplemental Indenture, dated as of August
26, 1997, among the Guarantor, United and Bankers Trust Company and (iii) the
Indenture, dated as of March 1,






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1996, between Sanifill, Inc. ("Sanifill") and Texas Commerce Bank National
Association, as supplemented by the First Supplemental Indenture, dated as of
September 3, 1996, among Sanifill, the Guarantor and Texas Commerce Bank
National Association) of the Guarantor (collectively, the "Guarantor's Senior
Debt") to the same extent as the Guarantor's guarantees of the Issuer's Liquid
Yield Option Notes due 2010 (Zero Coupon -- Subordinated) and Convertible
Subordinated Notes due 2005 (the "Guarantor's Subordinated Guarantees") and (b)
pari passu with the Guarantor's Subordinated Guarantees and the Guarantor's 5%
Convertible Subordinated Notes due 2006, 4 1/2% Convertible Subordinated Notes
due 2001 and 4% Convertible Subordinated Debentures due 2002.

                   SECTION 4. Waiver; Subrogation. (a) The Guarantor hereby
waives diligence, presentment, demand of payment, filing of claims with a court
in the event of merger or bankruptcy of the Issuer, any right to require a
proceeding filed first against the Issuer, protest or notice with respect to the
Debt Securities or the indebtedness evidenced thereby and all demands
whatsoever.

                   (b) The Guarantor shall be subrogated to all rights of the
Trustee or the holders of any Debt Securities against the Issuer in respect of
any amounts paid to the Trustee or such holder by the Guarantor pursuant to the
provisions of this Guarantee; provided, however, that the Guarantor shall not be
entitled to enforce, or to receive any payments arising out of or based upon,
such right of subrogation until all Obligations shall have been paid in full.

                   SECTION 5. No Waiver; Remedies. No failure on the part of any
holder of the Debt Securities to exercise, and no delay in exercising, any right
hereunder shall operate as a waiver thereof; nor shall any single or partial
exercise of any right hereunder preclude any other or further exercise thereof
or the exercise of any other right. The remedies herein provided are cumulative
and not exclusive of any remedies provided by law.

                   SECTION 6. Continuing Guarantee; Transfer of Interest. This
Guarantee is a continuing guaranty and shall (i) remain in full force and effect
until the earliest to occur of (A) the date, if any, on which the Guarantor
shall consolidate with or merge into the Issuer or any successor thereto, (B)
the date, if any, on which the Issuer or any successor thereto shall consolidate
with or merge into the Guarantor, (C) payment in full of the Obligations and (D)
the release by (1) the Banks under the Loan Agreement, dated as of July 16,
1998, by and among the Guarantor, the Issuer (as guarantor) and the Banks, the
Administrative Agent, the Documentation Agent and the Syndication Agents named
therein (or under any replacement or new principal credit facility of the
Issuer) of the guarantee of the Issuer thereunder and (2) the Banks under the
Second Amended and Restated Revolving Credit Agreement, dated as of July 16,
1998, by and among the Guarantor, the Issuer (as guarantor), Bank of America
National Trust and Savings Association, Morgan Guaranty Trust Company of New
York and each of the Banks named therein (or under any replacement or new
principal credit facility of the Issuer) of the guarantee of the Issuer
thereunder, (ii) be binding upon the Guarantor, its successors and assigns, and
(iii)






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inure to the benefit of and be enforceable by any holder of Debt Securities, the
Trustee, and by their respective successors, transferees, and assigns.

                   SECTION 7. Reinstatement. This Guarantee shall continue to be
effective or be reinstated, as the case may be, if at any time any payment of
any of the Obligations is rescinded or must otherwise be returned by any holder
of the Debt Securities or the Trustee upon the insolvency, bankruptcy or
reorganization of the Issuer or otherwise, all as though such payment had not
been made.

                   SECTION 8. Amendment. The Guarantor may amend this Guarantee
at any time for any purpose without the consent of the Trustee or any holder of
the Debt Securities.

                   SECTION 9.  Governing Law.  THIS GUARANTEE SHALL BE GOVERNED
BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK, WITHOUT REGARD TO THE PROVISIONS THEREOF RELATING TO CONFLICT
OF LAWS.

                   IN WITNESS WHEREOF, the Guarantor has caused this Guarantee
to be duly executed and delivered by its officer thereunto duly authorized as of
the date first above written.


                                       WASTE MANAGEMENT, INC.


                                       By:    /s/ Earl E. DeFrates
                                          --------------------------------------
                                             Name:  Earl E. DeFrates
                                             Title: Executive Vice President and
                                                      Chief Financial Officer