EXHIBIT 10.1

                                     WAIVER

      WAIVER dated as of March 31, 1998 to the AMENDED AND RESTATED CREDIT
AGREEMENT dated as of March 25, 1994 (as heretofore amended, the "CREDIT
AGREEMENT") among SAFETY-KLEEN CORP., the BANKS signatory thereto and THE CHASE
MANHATTAN BANK (successor by merger to The Chase Manhattan Bank, N.A.), as
Agent. Terms defined in the Credit Agreement are used herein as therein defined.

      WHEREAS, the Company has requested that the Banks waive any Event of
Default under Sections 9.01(c) and (j) of the Credit Agreement which may result
from the acquisition of the Borrower's common stock by LES Acquisition, Inc.
pursuant to that certain Agreement and Plan of Merger dated as of March 16, 1998
between the Borrower and Laidlaw Environmental Services, Inc.;

      WHEREAS, the Required Banks are agreeable to such request;

      NOW, THEREFORE, the parties hereto agree as follows:

      1. WAIVER. For the period commencing on the date hereof and ending on the
earlier of (i) June 30, 1998 and (ii) the date on which the merger of LES
Acquisition, Inc. and the Borrower (the "Merger) is consummated pursuant to
that certain Agreement and Plan of Merger dated as of March 16, 1998 between the
Borrower, LES Acquisition, Inc. and Laidlaw Environmental Services, Inc., the
Banks hereby waive any Event of Default which may occur under Section
9.01(c)(i) (as the result of non-compliance with Section 7.08 of the Credit
Agreement) or 9.01(j) of the Credit Agreement as the result of the Merger.

      2. REPRESENTATIONS AND WARRANTIES. The Company hereby represents and
warrants that: (a) the representations and warranties contained in Article 5 of
the Credit Agreement are true and correct on the date hereof as though made on
the date hereof, except in Section 5.05, the date specified as January 2, 1993
should be deleted and replaced with January 2, 1997 and the dates specified as
September 11, 1993 should be deleted and replaced with September 11, 1997; and
(b) after giving effect to this Waiver, no Default or Event of Default has
occurred and is continuing.

      3. EFFECT OF WAIVER. This Waiver does not constitute a waiver of any other
provision of the Credit Agreement or a waiver of any right, power or privilege
of the Banks or the Agent or of any future compliance with Sections 7.08 or any
other provision of the Credit Agreement. On and after the date this Waiver
becomes effective in accordance with Section 4 hereof, each reference in the
Credit Agreement to "this Agreement", "hereunder", "hereof", or words of like
import referring to the Agreement, and each reference in the Notes referring to
"the Agreement", "thereunder", "thereof", or words of like import shall mean the
Credit Agreement as amended by this Amendment. The Credit Agreement, as amended
by this Waiver, is and shall continue to be in full force and effect and is
hereby ratified and confirmed in all respects.

      4. MISCELLANEOUS. This Waiver (i) may be executed in one or more
counterparts by the parties hereto, (ii) shall become effective when
counterparts hereof have been executed by the parties, and (iii) SHALL BE
GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE
STATE OF NEW YORK.

      IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of
this Amendment to be duly executed and delivered as of the date first above
written.

                                    SAFETY-KLEEN CORP.


                                    By  /s/ LAURENCE M. RUDNICK
                                        ----------------------------
                                        Name:  Laurence M. Rudnick
                                        Title: Treasurer





                                    THE CHASE MANHATTAN BANK,
                                    as a Bank and as Agent


                                    By  /s/ KAREN M. SHARF
                                        -----------------------------
                                        Name:  Karen M. Sharf
                                        Title: Vice President


                                    THE NORTHERN TRUST COMPANY


                                    By  /s/ MICHELLE M. TETEAK
                                        -----------------------------
                                        Name:  Michelle M. Teteak
                                        Title: Vice President


                                    THE FIRST NATIONAL BANK OF CHICAGO


                                    By  /s/ BARRY P. LITWIN
                                        ------------------------------
                                        Name:  Barry P. Litwin
                                        Title: Senior Vice President



                                    NBD BANK (Successor to NBD Bank, N.A.)


                                    By  /s/ BARRY P. LITWIN
                                        -------------------------------
                                        Name:  Barry P. Litwin
                                        Title: Senior Vice President