THIS  DOCUMENT  IS A COPY OF THE FORM 10-Q FILED ON MAY 17,  2000  PURSUANT TO A
RULE 201 TEMPORARY HARDSHIP EXEMPTION.


--------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 10-Q


       QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
                              EXCHANGE ACT OF 1934


                For the Quarterly Period Ended May 31, 2000


                         Commission File Number 1-8368


                               SAFETY-KLEEN CORP.
                               ------------------
             (Exact name of registrant as specified in its charter)


         Delaware                                                51-0228924
-------------------------------                               ------------------
(State or other jurisdiction of                              (I.R.S. Employer
 incorporation or organization)                              Identification No.)


1301 Gervais Street Columbia, Suite 300, South Carolina                 29201
-------------------------------------------------------               ----------
(Address of principal executive offices)                              (Zip Code)

       (803) 933-4200 (Registrant's telephone number, including area code)
       --------------


            --------------------------------------------------------
   (Former name, address and former fiscal year, if changed since last report)

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Sections 13 or 15(d) of the  Securities  Exchange Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days.

                            Yes        No  X
                                ----      ----
         The number of shares of the  issuer's  common stock  outstanding  as of
July 10, 2000 was 100,783,596.

--------------------------------------------------------------------------------
<PAGE>




                               SAFETY-KLEEN CORP.


                                      INDEX


PART I FINANCIAL INFORMATION................................................3

PART II  OTHER INFORMATION

Item 1   Legal Proceedings..................................................3

Item 3   Defaults Upon Senior Securities....................................7

Item 6   Exhibits and Reports on Form 8-K...................................8

Signatures.................................................................16

Exhibit Index..............................................................17


                                     Page 2
<PAGE>



                         PART I - FINANCIAL INFORMATION

         Due to the ongoing internal  investigation of Safety-Kleen Corp.'s (the
"Company") reported financial results and certain of its accounting policies and
practices,  as announced by the Company on March 6, 2000,  the Company is unable
to prepare financial statements for the quarter ended May 31, 2000 at this time.
The Company will file amended reports as soon as practicable.

                           PART II - OTHER INFORMATION

ITEM 1.  LEGAL PROCEEDINGS.

GENERAL

         The business of the Company's  hazardous and industrial  waste services
is continuously  regulated by federal,  state,  provincial and local  provisions
that have been enacted or adopted,  regulating  the discharge of materials  into
the environment or primarily for the purpose of protecting the environment.  The
nature of the Company's businesses results in its frequently becoming a party to
judicial or  administrative  proceedings  involving  all levels of  governmental
authorities and other interested parties. The issues that are involved generally
relate to  applications  for  permits  and  licenses  by the  Company  and their
conformity with legal requirements and alleged technical  violations of existing
permits and  licenses.  The Company  does not believe  that these issues will be
material to the Company's  operations or financial  condition.  At May 31, 2000,
subsidiaries of the Company were involved in two proceedings  relating primarily
to  activities at waste  treatment,  storage and disposal  facilities  where the
Company believes  sanctions  involved in each instance may exceed $100,000.  The
Company  believes that the ultimate  disposition of these issues will not have a
materially adverse effect upon the Company's  consolidated financial position or
results of operations.

         From time to time,  the  Company  is named as a  defendant  in  various
lawsuits  arising in the  ordinary  course of  business,  including  proceedings
wherein  persons  claim injury  resulting  from the use of the  Company's  parts
cleaner equipment and/or cleaning  products,  other matters  involving  personal
injury and property  damage claims and  employment-related  claims.  A number of
such legal proceedings are currently pending in various courts and jurisdictions
throughout North America.  Based on the Company's assessment of known claims and
its historical claims payment pattern, and discussions with internal and outside
legal counsel and risk management personnel,  the Company believes that there is
no proceeding  pending against the Company  relating to such matters arising out
of the ordinary course of business that, if resolved against the Company,  would
have a  materially  adverse  effect upon the  Company's  consolidated  financial
position or results of operations.

         In the United States, CERCLA imposes financial liability on persons who
are  responsible for the release of hazardous  substances into the  environment.
Present  and  past  owners  and  operators  of  sites  which  release  hazardous
substances,  as well as generators and  transporters of the waste material,  are
jointly and severally liable for remediation costs and environmental  damage. At
May  31,  2000,  the  Company  had  been  notified  that  it  was a  potentially
responsible  party  in  connection  with 50  locations  in its  hazardous  waste
management and other businesses.

                                     Page 3
<PAGE>


The Company continually reviews its status with respect to each location and the
extent of its alleged  contribution to the volume of waste at the location,  the
available evidence connecting the Company to that location,  and the numbers and
financial  soundness of other potentially  responsible  parties at the location.
Based upon presently  available  information,  the Company does not believe that
potential  liabilities arising from its involvement with these locations will be
material to the Company's operations or financial condition.

CHAPTER 11 FILING

         As previously  announced by the Company in a Current Report on Form 8-K
filed on June 19, 2000,  Safety-Kleen  Corp. and 73 of its wholly owned domestic
subsidiaries filed a voluntary  petition for reorganization  under Chapter 11 of
Title 11 of the United  States Code on June 9, 2000.  The  petition was filed in
the United  States  Bankruptcy  Court for the  District  of  Delaware  (Case No.
00-2303  (PJW).  Management of the Company  continues to operate the business of
the Company as a debtor in possession under 11 U.S.C.  ss.ss.  1107 and 1108. In
this proceeding,  the Company and its subsidiaries  will seek approval of a Plan
for  Reorganization  and intend to implement  the Plan for  Reorganization  upon
obtaining court approval of the Plan.   Pursuant to the automatic stay provision
of  Section  362 of  the Bankruptcy  Code all  litigation matters are  currently
stayed.



SAFETY-KLEEN (PINEWOOD), INC.

         The Company's  reports on this matter contained in the Company's Report
on Form 10-K for the twelve  months  ended  August 31, 1999 and on Form 10-Q for
the quarters  ended  November 30, 1999 and February 28, 2000,  are  incorporated
herein by reference thereto.

         On May 4, 2000,  Pinewood  petitioned the South Carolina  Supreme Court
for a writ of certiorari from the state Court of Appeals decision.

         On June 9, 2000 (on the same day but after  Pinewood filed its petition
for bankruptcy  protection in the United States  District Court for the District
of Delaware),  DHEC issued an Emergency  Order  finding that Frontier  Insurance
Company - which is the issuer of bonds used to provide  for  Pinewood's  closure
cost,  post-closure  cost, and third party  liability  financial  assurance - no
longer meets regulatory standards for bond issuers.  Based on this finding, DHEC
ordered that  Pinewood  cease  accepting  waste for disposal by August 28, 2000,
unless it could provide acceptable  alternative  financial assurance by June 27,
2000.

         On June 13, 2000,  the South Carolina  Supreme Court denied  Pinewood's
petition  for a writ of  certiorari  and the  decision  of the Court of  Appeals
became final.

         On June 14, 2000,  DHEC sent notice by letter to the Pinewood  Facility
directing that Pinewood cease  accepting waste for disposal in 30 days - by July
14,  2000 - and  submit  a  closure  plan.  DHEC  based  this  directive  on the
then-final  decision  of the  Court  of  Appeals  that all  non-hazardous  waste
disposed  at  Pinewood  should be counted  against  Pinewood's  hazardous  waste
capacity  limit and  DHEC's  resulting  conclusion  that  there is no  remaining
permitted capacity at Pinewood.


                                     Page 4
<PAGE>


         On June 22, 2000, DHEC sent notice by letter to Pinewood that under the
Court of Appeals decision,  financial  assurance  regulations for cleanup and/or
environmental impairment restoration at hazardous waste treatment,  storage, and
disposal  facilities were vacated and,  therefore,  this financial assurance for
Pinewood must be provided in accordance  with the DHEC Board Order dated May 19,
1994.  The June 22, 2000 letter  further  directed  that within 15 days Pinewood
provide DHEC with information on how Pinewood would comply with the May 19, 1994
DHEC Board Order including payment into the GSX Contribution Fund. As of May 31,
2000, the GSX Contribution Fund contained $18,748,552.05, which means that under
the June 22,  2000 DHEC letter  Pinewood  would be  required  to  currently  pay
approximately  $68  million  into  the GSX  Contribution  Fund,  as well as make
payments of approximately $14 million each year for the next four years to reach
the full funding requirement.

         On July 7, 2000,  Pinewood  filed a legal action in  the United  States
District for the District of Delaware against the State of South Carolina, DHEC,
DHEC Board Chairman  (Bradford W. Wyche) and DHEC Commissioner  (Douglas Bryant)
under the caption: In Re:  Safety-Kleen Corp., et al.,  Debtor-Chapter 11 Cases,
Case No. 00-2303 Jointly Administered - Adversary Proceeding No. A-00-698,  C.A.
No.  00-637.  In this action  Pinewood  seeks to stay and/or enjoin DHEC and the
State of South Carolina from enforcement of the previously-described  directives
to Pinewood  set forth in the June 9, 2000 DHEC  Emergency  Order,  the June 14,
2000 DHEC letter to Pinewood, and the June 22, 2000 DHEC letter to Pinewood upon
the grounds that the actions of DHEC are invalid under various provisions of the
United States  Constitution  and/or  violate the automatic stay provision of the
United  States  Bankruptcy  Code and/or  should be enjoined  under the equitable
powers of the  Bankruptcy  Court.  As an alternative  cause of action,  Pinewood
demanded  that it be  compensated  for the taking of its  property  without just
compensation  under provisions of the Constitutions of the United States and the
State of South Carolina.

         On July 10, 2000, the United States  District Court for the District of
Delaware issued an Order  restraining  DHEC and the State of South Carolina from
enforcing its anticipated  closure of the Pinewood facility pursuant to the June
14, 2000 DHEC letter.  On July 12, 2000 the United States District Court for the
District of Delaware issued an Order  transferring the case to the United States
District Court for the District of South Carolina and ordering that the Order of
July 10, 2000  remain in full force and effect  pending a ruling from the United
States  District Court for the District of South Carolina on Pinewood's  request
for a preliminary injunction against DHEC and the State of South Carolina.

         If none of the  challenges  to the  decision of the Court of Appeals is
successful,  enforcement  of the decision  could have a material  adverse impact
upon the Company's financial position.

MATTERS RELATED TO INVESTIGATION OF FINANCIAL RESULTS

        The Company's report on this matter contained in the Company's Report on
Form 10-Q for the quarter  ended  February  28, 2000 is  incorporated  herein by
reference thereto. In the Report on Form 10-Q for the quarter ended February 28,
2000 the Company  reported  that  it anticipated  that additional  Federal Class
Actions may be filed.  Additional  Federal  Class  Actions  that have


                                     Page 5
<PAGE>


been filed are as follows:


<TABLE>

No.               CASE NAME                           COURT             DOCKET #         DATE OF         CLASS PERIOD
                                                                                         FILING
<S>  <C>                                        <C>                   <C>               <C>             <C>


1.   Muzinich & Co., Individually and on        United States         3:00-1145-17      4/13/00         7/7/98 - 3/5/00
     Behalf of All Others Similarly Situated    District Court
     v. Safety-Kleen Corp., Kenneth W.          (Columbia Division)
     Winger, Paul R. Humphreys and Michael
     Bragagnolo

2.   Yong Gen Cai, Individually and on Behalf   United States         3:00-0995-17      3/29/00         7/7/98 - 3/3/00
     of All Others Similarly Situated v.        District Court
     Safety-Kleen Corp., Kenneth W. Winger,     (Columbia Division)
     Paul R. Humphreys and Michael Bragagnolo


3.   Richard Weaver, Individually and on        United States         3:00-1012-17      3/30/00         7/7/98 - 3/3/00
     Behalf of All Others Similarly Situated    District Court
     v. Safety-Kleen Corp., Kenneth W.          (Columbia Division)
     Winger, Paul R. Humphreys and Michael
     Bragagnolo

4.   James K. Hodge, Individually and on        United States         3:00-0974-17      3/28/00         7/7/98 - 3/6/00
     Behalf of All Others Similarly Situated    District Court
     v. Safety-Kleen Corp., Kenneth W.          (Columbia Division)
     Winger, Paul R. Humphreys and Michael
     Bragagnolo

5.   Michael A. Collins and Laurie Collins,     United States         3:00-1408-17      5/08/00         Holders of Rollins
     on Behalf of Themselves and All Others     District Court                                          Environmental
     Similarly Situated v. Safety-Kleen         (Columbia Division)                                     Services shares as of
     Corp., a Delaware Corporation,  Kenneth                                                            5/3/97
     W. Winger, Paul R. Humphreys, Michael
     Bragagnolo and James R. Bullock

</TABLE>


                                     Page 6
<PAGE>

<TABLE>



No.               CASE NAME                           COURT             DOCKET #         DATE OF         CLASS PERIOD
                                                                                         FILING
<S>  <C>                                        <C>                   <C>               <C>             <C>

6.   Walter E. Ryan, on Behalf of Himself and   United States         3:00-1343-17      5/01/00         Holders of Rollins
     All Others Similarly Situated v.           District Court                                          Environmental
     Safety-Kleen Corp., a Delaware             (Columbia Division)                                     Services shares as of
     Corporation,  Kenneth W. Winger, Paul R.                                                           5/3/97
     Humphreys, Michael Bragagnolo and James                                            Amended
     R. Bullock                                                                         Summons
                                                                                        ed 5/10/00

7.   Walter E. Ryan, Jr., on Behalf of          United States         3:00-1394-17      5/05/00         7/9/97 - 3/6/00
     Himself and All Others Similarly           District Court
     Situated v. Safety-Kleen Corp., a          (Columbia Division)
     Delaware Corporation,  Kenneth W.
     Winger, Paul R. Humphreys, Michael
     Bragagnolo and James R. Bullock

8.   Kenneth Steiner, on Behalf of Himself      United States         3:00-750-17       5/01/00         11/13/97 - 4/17/98
     and All Others Similarly Situated v.       District Court                                          for old Safety-Kleen
     Kenneth W. Winger,  James R. Bullock,      (Columbia Division)                                     shareholders
     Paul R. Humphreys, Michael Bragagnolo
     and Safety-Kleen Corp.                                                             Amended
                                                                                        Summons
                                                                                        Filed 5/10/00
</TABLE>

         Other than as herein reported there have been no additional significant
legal proceedings or any material changes in the legal  proceedings  reported in
PART II, Item 3 of the Company's Report on Form 10-K for the twelve months ended
August 31, 1999.


ITEM 3.  DEFAULTS UPON SENIOR SECURITIES.

         During the quarter ended May 31, 2000, the Company and its subsidiaries
defaulted upon the following senior securities:

         The  Company  did not make an interest  payment of  approximately  $1.8
million due May


                                     Page 7
<PAGE>

30, 2000 upon the $60 million Promissory Note dated May 15, 1997 originally from
the Company to  Westinghouse  Electric  Corporation  and thereafter  assigned by
Westinghouse  Electric  Corporation  to Toronto  Dominion  (Texas) Inc. (the $60
million  Promissory  Note).  The grace period to make this payment expired after
the quarter  ended.  The holder did not  exercise  its right to  accelerate  the
payment of principal and interest. The total arrearage (without acceleration) on
the $60  million  Promissory  Note as of July  14,  2000 is  approximately  $2.7
million.

         The  Company  did not make an  interest  payment of  approximately  $10
million due May 15, 2000 on its 9 1/4 percent  Senior Notes due 2008.  The grace
period to make this interest payment expired after the quarter ended. The holder
did not exercise its right to accelerate  the payment of principal and interest.
The total arrearage  (without  acceleration)  on the Senior Notes due 2008 as of
July 14, 2000 is approximately $14 million.

         The Company  did not make  principal  and  interest  payments  totaling
approximately $43 million due May 31, 2000 under its Amended and Restated Credit
Agreement dated as of April 3, 1998 among Safety-Kleen Services,  Inc. (formerly
known as LES,  Inc.),  Safety-Kleen  Services  (Canada) Ltd.  (formerly known as
Laidlaw  Environmental  Services  (Canada) Ltd.), the Lenders,  Toronto Dominion
(Texas),  Inc., The Toronto Dominion Bank, TD Securities (USA) Inc., The Bank of
Nova Scotia, NationsBank,  N.A., The First National Bank of Chicago and Wachovia
Bank N.A.  (the  "Credit  Facility").  The grace  period to make these  payments
expired  after the  quarter  ended.  The  holder did not  exercise  its right to
accelerate the payment of principal and interest.  The total arrearage  (without
acceleration) on the Credit Facility as of July 14, 2000 is approximately  $71.9
million.

         In addition to the  aforementioned  defaults for nonpayment the Company
and its  subsidiaries  are in  default  of  certain  covenants  under  the above
described Credit Facility and the $60 million  Promissory Note and the Indenture
of Trust dated as of July 1, 1997 between Tooele County, Utah and U.S. Bank; the
Indenture of Trust dated as of July 1, 1997 between California Pollution Control
Financing Authority and U.S. Bank; Indenture of Trust dated as of August 1, 1995
between Tooele County,  Utah and West One Bank; the Indenture dated as of May 1,
1993 between  Industrial  Development  Board of the  Metropolitan  Government of
Nashville and Davidson County (Tennessee) and NationsBank of Tennessee, N.A. and
the Indenture  dated as of May 17, 1999 between the Company and the Bank of Nova
Scotia Trust Company.


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K.

     (a)   Exhibits:

(3)(a) Restated  Certificate of  Incorporation of the Company dated May 13, 1997
and  Amendment  to  Certificate  of  Incorporation  dated May 15,  1997 filed as
Exhibit 3(a) to the  Company's  Form 10-Q for the Quarter ended May 31, 1997 and
incorporated herein by reference.

(3)(a)(i)  Certificate  of  Correction  Filed to Correct a Certain  Error in the
Restated and Amended  Certificate of  Incorporation of the Company dated October
15, 1997 filed as Exhibit  (3)(a)(i) to the Company's Form 10-K-405 for the Year
ended August 31, 1997, and incorporated herein by reference.

(3)(a)(ii) Certificate of Amendment to the Restated Certificate of Incorporation
of the  Company  dated  November  25, 1998 filed as Exhibit  (3)(a)(iii)  to the
Company's  Form 10-Q for the quarter  ended  November 30, 1998 and  incorporated
herein by reference.


                                     Page 8
<PAGE>


(3)(a)(iii)   Certificate   of  Amendment  to  the   Restated   Certificate   of
Incorporation of the Company dated November 30, 1998 filed as Exhibit (3)(a)(iv)
to the  Company's  Form  10-Q  for the  quarter  ended  November  30,  1998  and
incorporated herein by reference.

(3)(b) Amended and Restated  Bylaws of the Company filed as Exhibit 4(ii) to the
Company's Current Report on Form 8-K dated July 29, 1997 and incorporated herein
by reference.

(4)(a) Indenture dated as of May 29, 1998 between LES, Inc. (a subsidiary of the
Company), the Company, subsidiary guarantors of the Company and The Bank of Nova
Scotia  Trust  Company  of New York,  as trustee  filed as  Exhibit  4(b) to the
Company's Form S-4 Registration  Statement No. 333-57587 filed June 24, 1998 and
incorporated herein by reference.

(4)(b)  First  Supplemental  Indenture  effective  as of November 15, 1998 among
Safety-Kleen  Services,  Inc., the Company, SK Europe, Inc. and The Bank of Nova
Scotia  Trust  Company of New York,  as trustee  filed as Exhibit  (4)(f) to the
Company's Form S-4 Registration  Statement No. 333-82689 filed July 12, 1999 and
incorporated herein by reference.

(4)(c)  Second  Supplemental  Indenture  effective  as  of  May  7,  1999  among
Safety-Kleen Services, Inc., the Company, SK Services, L.C., SK Services (East),
L.C. and The Bank of Nova Scotia Trust  Company of New York, as trustee filed as
Exhibit   (4)(d)  to  the  Company's  Form  10-K  filed  October  29,  1999  and
incorporated herein by reference.

(4)(d)  Indenture  dated as of May 17, 1999  between the Company and the Bank of
Nova Scotia Trust Company of New York, as trustee filed as Exhibit (4)(b) to the
Company's Form S-4 Registration  Statement No. 333-82689 filed July 12, 1999 and
incorporated herein by reference.

(4)(e)  Registration  Rights  Agreement  dated as of May 17,  1999  between  the
Company and TD  Securities,  NationsBanc  Montgomery  Securities LLC and Raymond
James &  Associates,  Inc.  filed as Exhibit  (4)(a) to the  Company's  Form S-4
Registration Statement No. 333-82689 filed July 12, 1999 and incorporated herein
by reference.

(4)(f) Amended and Restated  Credit  Agreement among Laidlaw  Chem-Waste,  Inc.,
Laidlaw Environmental Services (Canada) Ltd., Toronto Dominion (Texas) Inc., The
Toronto-Dominion  Bank,  TD  Securities  (USA)  Inc.,  The Bank of Nova  Scotia,
NationsBank,  N.A. and The First National Bank of Chicago and NationsBank,  N.A.
as  Syndication  Agent dated as of April 3, 1998,  filed as Exhibit  4(f) to the
Company's Form 10-Q for the quarter ended  February 28, 1999,  and  incorporated
herein by reference.

(4)(g)  Supplement to the Amended and Restated  Credit  Agreement  among Laidlaw
Chem-Waste, Inc., Laidlaw Environmental Services (Canada) Ltd., Toronto Dominion
(Texas) Inc., The  Toronto-Dominion  Bank, TD Securities (USA) Inc., The Bank of
Nova  Scotia,  NationsBank,  N.A.  and The First  National  Bank of Chicago  and
NationsBank,  N.A.  as  Syndication  Agent  dated as of April 3, 1998,  filed as
Exhibit 4(e) to a subsidiary of the Company's  Form S-4  Registration  Statement
No. 333-57587 filed June 24, 1998 and incorporated herein by reference.

(4)(h) Waiver and First Amendment to the Amended and Restated  Credit  Agreement
dated  as of May 15,  1998  among  LES,  Inc.,  Laidlaw  Environmental  Services
(Canada) Ltd., the Lenders, Toronto Dominion (Texas), Inc., The Toronto Dominion
Bank, TD Securities (USA) Inc., The


                                     Page 9
<PAGE>


Bank of Nova Scotia,  NationsBank,  N.A., The First National Bank of Chicago and
Wachovia Bank filed as Exhibit 4(f) to a subsidiary  of the  Company's  Form S-4
Registration Statement No. 333-57587 filed June 24, 1998 and incorporated herein
by reference.

(4)(i)  Commitment  to Increase  Supplement  to the Amended and Restated  Credit
Agreement  dated as of June 3,  1998  among  LES,  Inc.,  Laidlaw  Environmental
Services (Canada) Ltd., the Lenders, Toronto Dominion (Texas), Inc., The Toronto
Dominion Bank, TD Securities  (USA) Inc., The Bank of Nova Scotia,  NationsBank,
N.A., The First National Bank of Chicago and Wachovia Bank filed as Exhibit 4(g)
to a subsidiary of the Company's Form S-4  Registration  Statement No. 333-57587
filed June 24, 1998 and incorporated herein by reference.

(4)(j) Second Amendment to the Amended and Restated Credit Agreement dated as of
November 20, 1998 among  Safety-Kleen  Services,  Inc.  (formerly  known as LES,
Inc.),   Safety-Kleen   Services  (Canada)  Ltd.   (formerly  known  as  Laidlaw
Environmental  Services  (Canada) Ltd.), the Lenders,  Toronto Dominion (Texas),
Inc.,  The Toronto  Dominion  Bank, TD Securities  (USA) Inc.,  The Bank of Nova
Scotia, NationsBank,  N.A., The First National Bank of Chicago and Wachovia Bank
N.A.,  filed as Exhibit  (4)(j) to the Company's Form 10-Q for the quarter ended
February 28, 1999 and incorporated herein by reference.

(4)(k) Waiver and Third Amendment to the Amended and Restated  Credit  Agreement
dated as of May 6, 1999 among  Safety-Kleen  Services,  Inc.  (formerly known as
LES,  Inc.),  Safety-Kleen  Services  (Canada) Ltd.  (formerly  known as Laidlaw
Environmental  Services  (Canada) Ltd.), the Lenders,  Toronto Dominion (Texas),
Inc.,  The Toronto  Dominion  Bank, TD Securities  (USA) Inc.,  The Bank of Nova
Scotia, NationsBank,  N.A., The First National Bank of Chicago and Wachovia Bank
N.A. filed as Exhibit (4)(l) to the Company's  Form S-4  Registration  Statement
No. 333-82689 filed July 12, 1999 and incorporated herein by reference.

(4)(l) Fourth  Amendment  dated as of March 13, 2000 to the Amended and Restated
Credit  Agreement  dated as of May 6, 1999  among  Safety-Kleen  Services,  Inc.
(formerly known as LES, Inc.),  Safety-Kleen  Services  (Canada) Ltd.  (formerly
known as Laidlaw  Environmental  Services  (Canada) Ltd.), the Lenders,  Toronto
Dominion (Texas), Inc., The Toronto Dominion Bank, TD Securities (USA) Inc., The
Bank of Nova Scotia,  NationsBank,  N.A., The First National Bank of Chicago and
Wachovia Bank N.A.

(4)(m)  Consent  dated as of March 16, 2000 to the Amended and  Restated  Credit
Agreement dated as of May 6, 1999 among  Safety-Kleen  Services,  Inc. (formerly
known as LES,  Inc.),  Safety-Kleen  Services  (Canada) Ltd.  (formerly known as
Laidlaw  Environmental  Services  (Canada) Ltd.), the Lenders,  Toronto Dominion
(Texas),  Inc., The Toronto Dominion Bank, TD Securities (USA) Inc., The Bank of
Nova Scotia, NationsBank,  N.A., The First National Bank of Chicago and Wachovia
Bank N.A.

(4)(n)  Deferral  and  Forbearance  Agreement  dated as of April 7,  2000 to the
Amended and Restated Credit Agreement dated as of May 6, 1999 among Safety-Kleen
Services,  Inc.  (formerly known as LES, Inc.),  Safety-Kleen  Services (Canada)
Ltd.  (formerly known as Laidlaw  Environmental  Services  (Canada)  Ltd.),  the
Lenders,   Toronto  Dominion  (Texas),  Inc.,  The  Toronto  Dominion  Bank,  TD
Securities  (USA) Inc.,  The Bank of Nova Scotia,  NationsBank,  N.A., The First
National Bank of Chicago and Wachovia Bank N.A.


                                     Page 10
<PAGE>


(4)(o)  Waiver,  dated as of May 1, 2000,  under the  Deferral  and  Forbearance
Agreement dated as of April 7, 2000 to the Amended and Restated Credit Agreement
dated as of April 3, 1998 )as amended,  supplemented or otherwise modified prior
to May 1, 2000 among Safety-Kleen Services,  Inc. (formerly known as LES, Inc.),
Safety-Kleen Ltd.  (successor to Safety-Kleen  Services (Canada) Ltd., which was
formerly known as Laidlaw  Environmental  Services (Canada) Ltd.)), the Lenders,
Toronto Dominion  (Texas),  Inc., The Toronto Dominion Bank, TD Securities (USA)
Inc., The Bank of Nova Scotia,  Bank of America  (formerly known as Nationsbank,
N.A.),  Bank  One,  N.A.  and  (formerly  known as The  First  National  Bank of
Chicago).

(4)(p)  Registration  Rights  Agreement  dated May 15,  1997 among the  Company,
Laidlaw  Transportation,  Inc. and Laidlaw Inc.,  the form of which was filed as
Exhibit B to Annex A to the  Company's  Definitive  Proxy  Statement on Form DEF
14A, filed on May 1, 1997 and incorporated herein by reference.

(4)(q)  Indenture  dated as of May 1, 1993  between the  Industrial  Development
Board  of  the   Metropolitan   Government  of  Nashville  and  Davidson  County
(Tennessee)  and  NationsBank of Tennessee,  N.A.,  filed as Exhibit 4(f) to the
Company's Form 10-Q for the Quarter ended May 31, 1997, and incorporated  herein
by reference.

(4)(r) Indenture of Trust dated as of August 1, 1995 between Tooele County, Utah
and West One Bank,  Utah, now known as U.S.  Bank, as Trustee,  filed as Exhibit
4(h) to the  Company's  form  10-Q  for the  Quarter  ended  May 31,  1997,  and
incorporated herein by reference.

(4)(s)  Indenture of Trust dated as of July 1, 1997 between Tooele County,  Utah
and U.S. Bank, a national banking association, as Trustee, filed as Exhibit 4(j)
to the Company's Form 10-Q for the Quarter ended May 31, 1997, and  incorporated
herein by reference.

(4)(t) Indenture of Trust dated as of July 1, 1997 between California  Pollution
Control Financing  Authority and U.S. Bank, a national banking  association,  as
Trustee,  filed as Exhibit 4(k) to the Company's Form 10-Q for the Quarter ended
May 31, 1997, and incorporated herein by reference.

(4)(u)  Promissory Note dated May 15, 1997 for  $60,000,000  from the Company to
Westinghouse Electric  Corporation,  filed as Exhibit 4(n) to the Company's Form
10-Q for the Quarter ended May 31, 1997, and incorporated herein by reference.

(4)(v) Letter dated May 7, 1999 from Toronto-Dominion  (Texas) Inc. (as assignee
of Westinghouse  Electric  Corporation) and agreed to by the Company and Laidlaw
Inc. amending the terms of the Promissory Note dated May 15, 1997 (as referenced
in  Exhibit   (4)(r))  filed  as  Exhibit  (4)(u)  to  the  Company's  Form  S-4
Registration Statement No. 333-82689 filed July 12, 1999 and incorporated herein
by reference.

(4)(w)  Guaranty  Agreement  dated May 15, 1997 by Laidlaw Inc. to  Westinghouse
Electric  Corporation  guaranteeing  Promissory  Note  dated  May 15,  1997  (as
referenced   in  Exhibit   (4)(s))   from  Company  to   Westinghouse   Electric
Corporation),  filed as Exhibit 4(o) to the Company's  Form 10-Q for the Quarter
ended May 31, 1997, and incorporated herein by reference.


                                     Page 11
<PAGE>


(4)(x) Collateral Account Pledge and Security Agreement dated as of May 17, 1999
among the Company,  The Bank of Nova Scotia Trust Company of New York, as escrow
agent and The Bank of Nova Scotia Trust Company of New York,  as trustee,  filed
as Exhibit (4)(d) to the Company's Form S-4 Registration Statement No. 333-82689
filed July 12, 1999 and incorporated herein by reference.

(4)(y)  Rights  Agreement  dated as of October 15, 1999  between the Company and
EquiServe  Trust  Company,  N.A., as Rights Agent,  filed as Exhibit (c)1 to the
Company's  Current Report on Form 8-K filed on October 15, 1999 and incorporated
herein by reference.

(4)(z) First Amendment to Rights Agreement,  dated as of March 17, 2000, between
Safety-Kleen  Corp. and Equiserve  Trust Company,  N.A. filed as Exhibit 99.1 to
the  Company's  Current  Report  on  Form  8-K  filed  on  March  17,  2000  and
incorporated herein by reference.

(4)(aa) Letter Agreement, dated October 12, 1999, between Safety-Kleen Corp. and
Laidlaw Inc.  filed as Exhibit 99.2 to the Company's  Current Report on Form 8-K
filed on March 17, 2000 and incorporated herein by reference.

(4)(bb) Other instruments  defining the rights of holders of nonregistered  debt
of the Company  have been  omitted  from this exhibit list because the amount of
debt  authorized  under any such  instrument  does not  exceed  10% of the total
assets of the Company and its subsidiaries. The Company agrees to furnish a copy
of any such instrument to the Commission upon request.

(10)(a) Agreement and Plan of Merger dated as of March 16, 1998 by and among the
Company,  LES Acquisition,  Inc., and Safety-Kleen Corp.  included as Annex A of
Safety-Kleen's  Revised Amended  Prospectus on Form 14D-9 filed as Exhibit 62 to
Safety-Kleen's  Amendment  No.  28 to  Schedule  14-9A on March  17,  1998,  and
incorporated herein by reference.

(10)(b) Stock  Purchase  Agreement  between  Westinghouse  Electric  Corporation
(Seller) and Rollins Environmental Services, Inc. (Buyer) for National Electric,
Inc. dated March 7, 1995.

(10)(c) Second  Amendment to Stock Purchase  Agreement (as referenced in Exhibit
(10)(b)  above),  dated May 15, 1997 among  Westinghouse  Electric  Corporation,
Rollins Environmental  Services, Inc. and Laidlaw Inc., filed as Exhibit 4(m) to
the  Company's  Form 10-Q for the Quarter ended May 31, 1997,  and  incorporated
herein by reference.

(10)(d) Rollins  Environmental  Services,  Inc. 1982 Incentive Stock Option Plan
filed with Amendment No. 1 to the Company's  Registration  Statement No. 2-84139
on Form S-1 dated June 24, 1983 and incorporated herein by reference.

(10)(e) Rollins Environmental Services, Inc. 1993 Stock Option Plan.

(10)(f)  Company's 1997 Stock Option Plan, filed as Exhibit 4.4 to the Company's
Registration  Statement  No.  333-41859 on Form S-8 dated  December 10, 1997 and
incorporated herein by reference.

(10)(g) First  Amendment to Company's  1997 Stock Option Plan,  filed as Exhibit
(10)(g) to the  Company's  Form 10-Q dated  January  14,  2000 and  incorporated
herein by reference.


                                     Page 12
<PAGE>


(10)(h)  Company's  Director's  Stock Option  Plan,  filed as Exhibit 4.5 to the
Company's  Registration  Statement No.  333-41859 on Form S-8 dated December 10,
1997 and incorporated herein by reference.

(10)(i)  First  Amendment  to  Company's  Director's  Stock Option Plan filed as
Exhibit  (10)(i)  to  the  Company's  Form  10-Q  dated  January  14,  2000  and
incorporated herein by reference.

(10)(j)  Stock  Purchase  Agreement  dated  February 6, 1997 among the  Company,
Laidlaw Inc., and Laidlaw Transportation,  Inc. filed as Exhibit A to Annex A to
the  Definitive  Proxy  Statement  on Form  DEF 14A  filed  on May 1,  1997  and
incorporated herein by reference.

(10)(k)  Executive  Bonus Plan for fiscal  year 2000 filed as  Appendix C to the
Definitive  Proxy  Statement  on Form DEF 14A  filed  on  October  29,  1999 and
incorporated herein by reference.

(10)(l) Company's U.S.  Supplemental  Executive Retirement Plan filed as Exhibit
10(g) to the Company's  Form 10-Q for the quarter ended  November 30, 1997,  and
incorporated  herein by reference.

(10)(m) Form of Change of Control  Agreement
A-12-22 filed as Exhibit 10(m) to the Company's  Form 10-Q for the quarter ended
February 29, 2000, and incorporated herein by reference.

(10)(n) Form of Change of Control  Agreement A1 RB 11 30 filed as Exhibit  10(n)
to the  Company's  Form  10-Q for the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.

(10)(o) Form of Change of Control  Agreement  A2-12-22 filed as Exhibit 10(o) to
the  Company's   Form  10-Q  for  the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.

(10)(p) Form of Change of Control  Agreement  AAMB0120 filed as Exhibit 10(p) to
the  Company's   Form  10-Q  for  the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.

(10)(q) Form of Change of Control  Agreement  B-12-22  filed as Exhibit 10(q) to
the  Company's   Form  10-Q  for  the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.

(10)(r) Form of Change of Control  Agreement  C-12-22  filed as Exhibit 10(r) to
the  Company's   Form  10-Q  for  the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.

(10)(s) Form of Change of Control  Agreement  D-12-22  filed as Exhibit 10(s) to
the  Company's   Form  10-Q  for  the  quarter  ended  February  29,  2000,  and
incorporated herein by reference.


                                     Page 13
<PAGE>


(10)(t)  Agreement  dated as of March 3, 2000,  among the Company,  Safety-Kleen
Services, Inc., Safety-Kleen Ltd. and Kenneth W. Winger.

(10)(u) Demand Loan Agreement among  Safety-Kleen  Systems,  Inc.,  Safety-Kleen
Services,  Inc. as  Guarantor  the  Several  Lenders  from time to time  parties
thereto and Toronto Dominion (Texas), Inc. as Agent dated as of March 14, 2000.

(10)(v)  Mortgage,  Assignment of Rents and Leases and Security  Agreement  from
Safety-Kleen Systems, Inc. Mortgagor to Toronto Dominion (Texas), Inc. Mortgagee
dated as of March 14,  2000.

(10)(w) Lien Subordination  Agreement between Toronto Dominion (Texas), Inc., as
Liquidity Agent and Toronto Dominion (Texas), Inc., as Existing Debt Agent dated
as of March 16, 2000.

(10)(x) Letter  Agreement dated March 16, 2000 between Jay Alix & Associates and
the Company.

     (b)      Reports on Form 8-K.

i.     The Company  filed a Current  Report on Form 8-K on March 6, 2000,  which
       contained Item 5 related to the Company announcing internal investigation
       of accounting practices.

ii.    The Company  filed a Current  Report on Form 8-K on March 9, 2000,  which
       contained   Item   5   related   to   the   Company    announcing    that
       PricewaterhouseCoopers  LLP advised the Company  that it was  withdrawing
       previously issued reports on financial statements.

iii.   The Company filed a Current  Report on Form 8-K on March 13, 2000,  which
       contained  Item 5 related to the Company  announcing  continued  internal
       investigation     of     accounting     practices,      withdrawal     of
       PricewaterhouseCoopers  reports, need for cash to fund current operations
       and SEC investigation.

iv.    The Company filed a Current  Report on Form 8-K on March 16, 2000,  which
       contained Item 5 related to the Company  announcing bank negotiations for
       interim  financing,  letter of intent to sell  former  headquarters,  and
       preliminary results of accounting investigation.

v.     The Company filed a Current  Report on Form 8-K on March 17, 2000,  which
       contained Item 5 related to the Company announcing $20 million additional
       credit  availability and an amendment to the Rights Agreement between the
       registrant and Equiserve Trust Company, N.A.

vi.    The Company filed a Current  Report on Form 8-K on March 21, 2000,  which
       contained  Item  5  related  to  the  Company   announcing   interim  CFO
       appointment,   retention  of  Jay  Alix  &  Associates   and   continuing
       negotiation with lenders.

vii.   The Company  filed a Current  Report on Form 8-K on April 4, 2000,  which
       contained  Item  5  related  to  the  Company   announcing   interim  CIO
       appointment.


                                     Page 14
<PAGE>


viii.  The Company  filed a Current  Report on Form 8-K on April 4, 2000,  which
       contained Item 5 related to the Company  announcing  delaying issuance of
       earnings report for the second quarter of 2000.

ix.    The Company  filed a Current  Report on Form 8-K on April 6, 2000,  which
       contained  Item 5  related  to the  Company  condolences  at the  loss of
       company director, John W. Rollins, Sr.

x.     The  Company  filed a Current  Report on Form 8-K on May 8,  2000,  which
       contained  Item 5 related to the Company  announcing  appointment  of new
       director, election of chairman.

xi.    The Company  filed a Current  Report on Form 8-K on May 15,  2000,  which
       contained   Item  5  related  to  the  Company   announcing   executive's
       resignations of positions.

xii.   The Company  filed a Current  Report on Form 8-K on May 17,  2000,  which
       contained  Item 5 related to the Company  announcing  it would no make an
       interest payment on the Company's 9 1/4 percent Senior Notes due 2009.


                                    Page 15
<PAGE>



                                   SIGNATURES

          Pursuant to the  requirements of the Securities  Exchange Act of 1934,
the  Company  has duly  caused  this  report to be  signed on its  behalf by the
undersigned thereunto duly authorized.

   DATE:  July 17, 2000                        SAFETY-KLEEN CORP.
                                               ------------------
                                               (Registrant)

                                               /s/ David E. Thomas, Jr.
                                               ------------------------------
                                               David E. Thomas, Jr.
                                               Chief Executive Officer and
                                                  Chairman of the Board


                                               /s/ Henry H. Taylor
                                               ------------------------------
                                               Henry H. Taylor
                                               Vice President, General Counsel
                                               & Secretary


                                     Page 16
<PAGE>


                                  EXHIBIT INDEX

(3)(a)       Restated  Certificate of Incorporation of the Company dated May 13,
             1997 and Amendment to  Certificate of  Incorporation  dated May 15,
             1997  filed as  Exhibit  3(a) to the  Company's  Form  10-Q for the
             Quarter ended May 31, 1997 and incorporated herein by reference.


(3)(a)(i)    Certificate  of Correction  Filed to Correct a Certain Error in the
             Restated and Amended  Certificate of  Incorporation  of the Company
             dated October 15, 1997 filed as Exhibit  (3)(a)(i) to the Company's
             Form 10-K-405 for the Year ended August 31, 1997, and  incorporated
             herein by reference.

(3)(a)(ii)   Certificate   of   Amendment  to  the   Restated   Certificate   of
             Incorporation  of the  Company  dated  November  25,  1998 filed as
             Exhibit  (3)(a)(iii)  to the  Company's  Form 10-Q for the  quarter
             ended November 30, 1998 and incorporated herein by reference.

(3)(a)(iii)  Certificate   of   Amendment  to  the   Restated   Certificate   of
             Incorporation  of the  Company  dated  November  30,  1998 filed as
             Exhibit (3)(a)(iv) to the Company's Form 10-Q for the quarter ended
             November 30, 1998 and incorporated herein by reference.

(3)(b)       Amended and Restated  Bylaws of the Company  filed as Exhibit 4(ii)
             to the Company's Current Report on Form 8-K dated July 29, 1997 and
             incorporated herein by reference.


(4)(a)       Indenture  dated as of May 29, 1998 between LES, Inc. (a subsidiary
             of the Company), the Company,  subsidiary guarantors of the Company
             and The Bank of Nova Scotia Trust  Company of New York,  as trustee
             filed  as  Exhibit  4(b) to the  Company's  Form  S-4  Registration
             Statement No. 333-57587 filed June 24, 1998 and incorporated herein
             by reference.

(4)(b)       First  Supplemental  Indenture  effective  as of November  15, 1998
             among Safety-Kleen Services,  Inc. the Company, SK Europe, Inc. and
             The Bank of Nova Scotia Trust Company of New York, as trustee filed
             as Exhibit (4)(f) to the Company's Form S-4 Registration  Statement
             No.  333-82689  filed  July 12,  1999 and  incorporated  herein  by
             reference.


(4)(c)       Second  Supplemental  Indenture  effective  as of May 7, 1999 among
             Safety-Kleen  Services,  Inc. the Company,  SK Services,  L.C.,  SK
             Services (East),  L.C. and The Bank of Nova Scotia Trust Company of
             New York, as trustee filed as Exhibit  (4)(d) to the Company's Form
             10-K filed October 29, 1999 and incorporated herein by reference.


                                    Page 17
<PAGE>


(4)(d)       Indenture dated as of May 17, 1999 between the Company and the Bank
             of Nova  Scotia  Trust  Company of New York,  as  trustee  filed as
             Exhibit (4)(b) to the Company's Form S-4 Registration Statement No.
             333-82689 filed July 12, 1999 and incorporated herein by reference.

(4)(e)       Registration  Rights Agreement dated as of May 17, 1999 between the
             Company and TD Securities,  NationsBanc  Montgomery  Securities LLC
             and Raymond James & Associates, Inc. filed as Exhibit (4)(a) to the
             Company's Form S-4 Registration  Statement No. 333-82689 filed July
             12, 1999 and incorporated herein by reference.

(4)(f)       Amended and Restated  Credit  Agreement  among Laidlaw  Chem-Waste,
             Inc.,  Laidlaw   Environmental   Services  (Canada)  Ltd.,  Toronto
             Dominion  (Texas) Inc.,  The  Toronto-Dominion  Bank, TD Securities
             (USA) Inc.,  The Bank of Nova  Scotia,  NationsBank,  N.A.  and The
             First National Bank of Chicago and NationsBank, N.A. as Syndication
             Agent  dated as of  April 3,  1998,  filed as  Exhibit  4(f) to the
             Company's  Form 10-Q for the quarter ended  February 28, 1999,  and
             incorporated herein by reference.


(4)(g)       Supplement  to the  Amended and  Restated  Credit  Agreement  among
             Laidlaw Chem-Waste,  Inc., Laidlaw Environmental  Services (Canada)
             Ltd., Toronto Dominion (Texas) Inc., The Toronto-Dominion  Bank, TD
             Securities (USA) Inc., The Bank of Nova Scotia,  NationsBank,  N.A.
             and The First  National  Bank of Chicago and  NationsBank,  N.A. as
             Syndication  Agent dated as of April 3, 1998, filed as Exhibit 4(e)
             to a subsidiary of the Company's  Form S-4  Registration  Statement
             No.  333-57587  filed  June 24,  1998 and  incorporated  herein  by
             reference.


(4)(h)       Waiver and First  Amendment  to the  Amended  and  Restated  Credit
             Agreement  dated  as of May  15,  1998  among  LES,  Inc.,  Laidlaw
             Environmental Services (Canada) Ltd., the Lenders, Toronto Dominion
             (Texas), Inc., The Toronto Dominion Bank, TD Securities (USA) Inc.,
             The Bank of Nova Scotia, NationsBank, N.A., The First National Bank
             of Chicago and Wachovia  Bank filed as Exhibit 4(f) to a subsidiary
             of the Company's  Form S-4  Registration  Statement  No.  333-57587
             filed June 24, 1998 and incorporated herein by reference.


(4)(i)       Commitment  to Increase  Supplement  to the  Amended  and  Restated
             Credit Agreement dated as of June 3, 1998 among LES, Inc.,  Laidlaw
             Environmental Services (Canada) Ltd., the Lenders, Toronto Dominion
             (Texas), Inc., The Toronto Dominion Bank, TD Securities (USA) Inc.,
             The Bank of Nova Scotia, NationsBank, N.A., The First National Bank
             of Chicago and Wachovia  Bank filed as Exhibit 4(g) to a subsidiary
             of the Company's  Form S-4  Registration  Statement  No.  333-57587
             filed June 24, 1998 and incorporated herein by reference.


                                    Page 18
<PAGE>


(4)(j)       Second Amendment to the Amended and Restated Credit Agreement dated
             as of November 20, 1998 among Safety-Kleen Services, Inc. (formerly
             known as LES, Inc.),  Safety-Kleen Services (Canada) Ltd. (formerly
             known  as  Laidlaw  Environmental   Services  (Canada)  Ltd.),  the
             Lenders, Toronto Dominion (Texas), Inc., The Toronto Dominion Bank,
             TD  Securities  (USA) Inc.,  The Bank of Nova Scotia,  NationsBank,
             N.A.,  The First  National  Bank of Chicago and Wachovia Bank N.A.,
             filed as Exhibit  (4)(j) to the Company's Form 10-Q for the quarter
             ended February 28, 1999 and incorporated herein by reference.


(4)(k)       Waiver and Third  Amendment  to the  Amended  and  Restated  Credit
             Agreement dated as of May 6, 1999 among Safety-Kleen Services, Inc.
             (formerly known as LES, Inc.),  Safety-Kleen Services (Canada) Ltd.
             (formerly known as Laidlaw  Environmental  Services (Canada) Ltd.),
             the Lenders,  Toronto Dominion (Texas),  Inc., The Toronto Dominion
             Bank,  TD  Securities   (USA)  Inc.,   The  Bank  of  Nova  Scotia,
             NationsBank,  N.A., The First National Bank of Chicago and Wachovia
             Bank  N.A.  filed  as  Exhibit  (4)(l)  to the  Company's  Form S-4
             Registration  Statement  No.  333-82689  filed  July  12,  1999 and
             incorporated herein by reference.


(4)(l)       Fourth  Amendment  dated as of March 13,  2000 to the  Amended  and
             Restated   Credit   Agreement   dated  as  of  May  6,  1999  among
             Safety-Kleen   Services,   Inc.  (formerly  known  as  LES,  Inc.),
             Safety-Kleen  Services  (Canada)  Ltd.  (formerly  known as Laidlaw
             Environmental   Services  (Canada)  Ltd.),  the  Lenders,   Toronto
             Dominion  (Texas),  Inc., The Toronto  Dominion Bank, TD Securities
             (USA) Inc., The Bank of Nova Scotia,  NationsBank,  N.A., The First
             National Bank of Chicago and Wachovia Bank N.A.

(4)(m)       Consent  dated as of March 16,  2000 to the  Amended  and  Restated
             Credit  Agreement  dated  as of  May  6,  1999  among  Safety-Kleen
             Services, Inc. (formerly known as LES, Inc.), Safety-Kleen Services
             (Canada) Ltd.  (formerly  known as Laidlaw  Environmental  Services
             (Canada) Ltd.), the Lenders,  Toronto Dominion  (Texas),  Inc., The
             Toronto  Dominion Bank, TD Securities  (USA) Inc., The Bank of Nova
             Scotia,  NationsBank,  N.A., The First National Bank of Chicago and
             Wachovia Bank N.A.


(4)(n)       Deferral and Forbearance Agreement dated as of April 7, 2000 to the
             Amended and Restated Credit Agreement dated as of May 6, 1999 among
             Safety-Kleen   Services,   Inc.  (formerly  known  as  LES,  Inc.),
             Safety-Kleen  Services  (Canada)  Ltd.  (formerly  known as Laidlaw
             Environmental   Services  (Canada)  Ltd.),  the  Lenders,   Toronto
             Dominion  (Texas),  Inc., The Toronto  Dominion Bank, TD Securities
             (USA) Inc., The Bank of Nova Scotia,  NationsBank,  N.A., The First
             National Bank of Chicago and Wachovia Bank N.A.

(4)(o)       (4)(o)  Waiver,  dated as of May 1, 2000,  under the  Deferral  and
             Forbearance  Agreement dated as of April 7, 2000 to the Amended and
             Restated  Credit  Agreement  dated as of April 3, 1998 )as amended,
             supplemented  or  otherwise  modified  prior to May 1,  2000  among
             Safety-Kleen   Services,   Inc.  (formerly  known


                                     Page 19
<PAGE>


             as  LES,  Inc.),   Safety-Kleen  Ltd.  (successor  to  Safety-Kleen
             Services  (Canada)  Ltd.,  which  was  formerly  known  as  Laidlaw
             Environmental  Services  (Canada)  Ltd.)),  the  Lenders,   Toronto
             Dominion  (Texas),  Inc., The Toronto  Dominion Bank, TD Securities
             (USA)  Inc.,  The Bank of Nova  Scotia,  Bank of America  (formerly
             known as Nationsbank,  N.A.), Bank One, N.A. and (formerly known as
             The First National Bank of Chicago).

(4)(p)       Registration Rights Agreement dated May 15, 1997 among the Company,
             Laidlaw  Transportation,  Inc. and Laidlaw Inc.,  the form of which
             was filed as Exhibit B to Annex A to the Company's Definitive Proxy
             Statement  on Form DEF 14A,  filed on May 1, 1997 and  incorporated
             herein by reference.


(4)(q)       Indenture   dated  as  of  May  1,  1993  between  the   Industrial
             Development  Board of the Metropolitan  Government of Nashville and
             Davidson County  (Tennessee)  and  NationsBank of Tennessee,  N.A.,
             filed as Exhibit  4(f) to the  Company's  Form 10-Q for the Quarter
             ended May 31, 1997, and incorporated herein by reference.


(4)(r)       Indenture  of Trust  dated as of  August  1,  1995  between  Tooele
             County,  Utah and West One Bank,  Utah,  now known as U.S. Bank, as
             Trustee,  filed as Exhibit 4(h) to the Company's  form 10-Q for the
             Quarter ended May 31, 1997, and incorporated herein by reference.


(4)(s)       Indenture of Trust dated as of July 1, 1997 between  Tooele County,
             Utah and U.S.  Bank, a national  banking  association,  as Trustee,
             filed as Exhibit  4(j) to the  Company's  Form 10-Q for the Quarter
             ended May 31, 1997, and incorporated herein by reference.


(4)(t)       Indenture  of Trust  dated as of July 1,  1997  between  California
             Pollution  Control  Financing  Authority and U.S.  Bank, a national
             banking  association,  as  Trustee,  filed as  Exhibit  4(k) to the
             Company's  Form  10-Q  for the  Quarter  ended  May 31,  1997,  and
             incorporated herein by reference.


(4)(u)       Promissory Note dated May 15, 1997 for $60,000,000 from the Company
             to Westinghouse Electric Corporation,  filed as Exhibit 4(n) to the
             Company's  Form  10-Q  for the  Quarter  ended  May 31,  1997,  and
             incorporated herein by reference.

(4)(v)       Letter  dated May 7, 1999 from  Toronto-Dominion  (Texas)  Inc. (as
             assignee of Westinghouse Electric Corporation) and agreed to by the
             Company and Laidlaw Inc.  amending the terms of the Promissory Note
             dated May 15,  1997 (as  referenced  in  Exhibit  (4)(r))  filed as
             Exhibit (4)(u) to the Company's Form S-4 Registration Statement No.
             333-82689 filed July 12, 1999 and incorporated herein by reference.

(4)(w)       Guaranty   Agreement   dated  May  15,  1997  by  Laidlaw  Inc.  to
             Westinghouse  Electric  Corporation  guaranteeing  Promissory  Note
             dated May 15, 1997 (as  referenced in Exhibit  (4)(s)) from Company
             to Westinghouse Electric Corporation), filed as Exhibit 4(o) to the
             Company's  Form  10-Q  for the  Quarter  ended  May 31,  1997,  and
             incorporated herein by reference.


                                     Page 20
<PAGE>


(4)(x)       Collateral  Account Pledge and Security  Agreement  dated as of May
             17, 1999 between the Company, The Bank of Nova Scotia Trust Company
             of New York,  as escrow  agent  and The Bank of Nova  Scotia  Trust
             Company of New York,  as  trustee,  filed as Exhibit  (4)(d) to the
             Company's Form S-4 Registration  Statement No. 333-82689 filed July
             12, 1999 and incorporated herein by reference.


(4)(y)       Rights  Agreement  dated as of October 15, 1999 between the Company
             and  EquiServe  Trust  Company,  N.A.,  as Rights  Agent,  filed as
             Exhibit (c)1 to the Company's  Current  Report on Form 8-K filed on
             October 15, 1999 and incorporated herein by reference.


(4)(z)       First  Amendment to Rights  Agreement,  dated as of March 17, 2000,
             between Safety-Kleen Corp. and Equiserve Trust Company,  N.A. filed
             as Exhibit 99.1 to the Company's  Current  Report on Form 8-K filed
             on March 17, 2000 and incorporated herein by reference.


(4)(aa)      Letter  Agreement,  dated  October 12, 1999,  between  Safety-Kleen
             Corp.  and  Laidlaw  Inc.  filed as Exhibit  99.2 to the  Company's
             Current Report on Form 8-K filed on March 17, 2000 and incorporated
             herein by reference.


(4)(bb)      Other  instruments  defining the rights of holders of nonregistered
             debt of the  Company  have  been  omitted  from this  exhibit  list
             because  the amount of debt  authorized  under any such  instrument
             does not  exceed  10% of the total  assets of the  Company  and its
             subsidiaries.  The  Company  agrees  to  furnish a copy of any such
             instrument to the Commission upon request.


(10)(a)      Agreement  and Plan of  Merger  dated as of March  16,  1998 by and
             among the Company,  LES Acquisition,  Inc., and Safety-Kleen  Corp.
             included as Annex A of Safety-Kleen's Revised Amended Prospectus on
             Form 14D-9 filed as Exhibit 62 to  Safety-Kleen's  Amendment No. 28
             to Schedule  14-9A on March 17, 1998,  and  incorporated  herein by
             reference.


(10)(b)      Stock Purchase Agreement between Westinghouse  Electric Corporation
             (Seller)  and  Rollins  Environmental  Services,  Inc.  (Buyer) for
             National Electric, Inc. dated March 7, 1995.


(10)(c)      Second  Amendment to Stock  Purchase  Agreement  (as  referenced in
             Exhibit  (10)(b)  above),  dated May 15,  1997  among  Westinghouse
             Electric  Corporation,  Rollins  Environmental  Services,  Inc. and
             Laidlaw Inc.,  filed as Exhibit 4(m) to the Company's Form 10-Q for
             the  Quarter  ended  May  31,  1997,  and  incorporated  herein  by
             reference.


(10)(d)      Rollins  Environmental  Services,  Inc. 1982 Incentive Stock Option
             Plan  filed  with  Amendment  No. 1 to the  Company's  Registration
             Statement  No.  2-84139  on  Form  S-1  dated  June  24,  1983  and
             incorporated herein by reference.


(10)(e)      Rollins Environmental Services, Inc. 1993 Stock Option Plan.


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<PAGE>


(10)(f)      Company's  1997 Stock  Option  Plan,  filed as  Exhibit  4.4 to the
             Company's  Registration  Statement No.  333-41859 on Form S-8 dated
             December 10, 1997 and incorporated herein by reference.


(10)(g)      First  Amendment  to Company's  1997 Stock  Option  Plan,  filed as
             Exhibit  (10)(g) to the Company's  Form 10-Q dated January 14, 2000
             and incorporated herein by reference.


(10)(h)      Company's Director's Stock Option Plan, filed as Exhibit 4.5 to the
             Company's  Registration  Statement No.  333-41859 on Form S-8 dated
             December 10, 1997 and incorporated herein by reference.


(10)(i)      First Amendment to Company's  Director's Stock Option Plan filed as
             Exhibit  (10)(i) to the Company's  Form 10-Q dated January 14, 2000
             and incorporated herein by reference.


(10)(j)      Stock Purchase  Agreement dated February 6, 1997 among the Company,
             Laidlaw Inc., and Laidlaw  Transportation,  Inc. filed as Exhibit A
             to Annex A to the Definitive  Proxy Statement on Form DEF 14A filed
             on May 1, 1997 and incorporated herein by reference.


(10)(k)      Executive  Bonus Plan for fiscal  year 2000 filed as  Appendix C to
             the Definitive Proxy Statement on Form DEF 14A filed on October 29,
             1999 and incorporated herein by reference.


(10)(l)      Company's  U.S.  Supplemental  Executive  Retirement  Plan filed as
             Exhibit 10(g) to the Company's  10-Q for the quarter ended November
             30, 1997, and incorporated herein by reference.

(10)(m)      Form of Change of Control  Agreement A-12-22 filed as Exhibit 10(m)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.


(10)(n)      Form of Change of  Control  Agreement  A1 RB 11 30 filed as Exhibit
             10(n) to the  Company's  10-Q for the quarter  ended  February  29,
             2000, and incorporated herein by reference.


(10)(o)      Form of Change of Control Agreement A2-12-22 filed as Exhibit 10(o)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.


(10)(p)      Form of Change of Control Agreement AAMB0120 filed as Exhibit 10(p)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.


(10)(q)      Form of Change of Control  Agreement B-12-22 filed as Exhibit 10(q)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.


                                     Page 22
<PAGE>


(10)(r)      Form of Change of Control  Agreement C-12-22 filed as Exhibit 10(r)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.


(10)(s)      Form of Change of Control  Agreement D-12-22 filed as Exhibit 10(s)
             to the Company's  10-Q for the quarter ended February 29, 2000, and
             incorporated herein by reference.

(10)(t)      Agreement   dated  as  of  March  3,  2000,   among  the   Company,
             Safety-Kleen  Services,  Inc.,  Safety-Kleen  Ltd.  and  Kenneth W.
             Winger.

(10)(u)      Demand   Loan   Agreement   among   Safety-Kleen   Systems,   Inc.,
             Safety-Kleen  Services,  Inc. as Guarantor the Several Lenders from
             time to time parties thereto and Toronto Dominion (Texas),  Inc. as
             Agent dated as of March 14, 2000.

(10)(v)      Mortgage,  Assignment  of Rents and Leases and  Security  Agreement
             from  Safety-Kleen  Systems,  Inc.  Mortgagor  to Toronto  Dominion
             (Texas),  Inc.  Mortgagee dated as of March 14, 2000.

(10)(w)      Lien  Subordination  Agreement  between Toronto  Dominion  (Texas),
             Inc., as Liquidity  Agent and Toronto  Dominion  (Texas),  Inc., as
             Existing Debt Agent dated as of March 16, 2000.

(10)(x)      Letter Agreement dated March 16, 2000 between Jay Alix & Associates
             and the Company.

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