EXHIBIT 10(a)
                                          AMENDMENT TO
                                    SCHERING-PLOUGH CORPORATION
                          SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

The Schering-Plough Corporation Supplemental Executive Retirement Plan 
(the "SERP"), as amended and restated to February 24, 1998, is hereby 
amended effective as of November 1, 1998 as follows:

1.  SECTION 1, Definitions, is hereby amended to add the following 
    new definition:

       "Change of Control Termination Date" means the date, following a 
        Change of Control, as of which a Participant or Former Participant 
        ceases to be an employee of the Corporation or any of its 
        Affiliates.

2.  SECTION 3, Eligibility for Benefits, is hereby amended by deleting 
Section 3.1 in its entirety and replacing it with the following language:

        "Each Participant or Former Participant is eligible to commence 
        receiving benefits under this Plan on one of the following dates, 
        as such dates are defined or provided for herein or in the relevant 
        Basic Plan, as applicable.

           (a)    Normal Retirement Date.

           (b)    Early Retirement Date.

           (c)    Deferred or Postponed Retirement Date.

           (d)    Change of Control Termination Date.

3.  SECTION 4.3 is hereby amended by deleting it in its entirety and replacing
it with the following language:

           "The Benefit of a Participant or Former Participant retiring on an 
           Early Retirement Date or terminating employment following a Change 
           of Control shall be an annual benefit payable monthly commencing on 
           the first day of the calendar month coincident with or next 
           following his Early Retirement Date or Change of Control 
           Termination Date, as the case may be, equal to 2% of his Average 
           Final Earnings multiplied by his years of Service in E-grade pay 
           status, or after ten years of Service in any pay status all Service 
           except Service subsequent to removal from E-grade pay status, up to 
           twenty years plus 1% of his Average Final Earnings for each such 
           year of Service in excess of twenty years, inclusive of his Other 
           Retirement Income and his Basic Plan Benefit, and reduced by the 
           following factors depending upon his age on such Early Retirement 
           Date or Change of Control Termination Date, as the case may be:


     Age at Early                          Age at Early
  Retirement Date                         Retirement Date
or Change of Control                     or Change of Control
  Termination Date     Reduction Factor  Termination Date       Reduction  
                                                                 Factor

      64                   0                49                      56%
      63                   0                48                      59%
      62                   0                47                      62%
      61                   4%               46                      65%
      60                   8%               45                    67.5%
      59                  12%               44                      70%
      58                  16%               43                      72%
      57                  20%               42                      74%
      56                  24%               41                      76%
      55                  28%               40                      78%
      54                33.5%               39                    79.5%
      53                  39%               38                      81%
      52                  44%               37                      82%
      51                  48%               36                      83%
      50                  52%               35                      84%

provided however, that the Benefit payable to a Participant or Former 
Participant who retires while an active employee on an Early Retirement Date 
on or after he has attained age 60 and has at least 10 years of Service in 
E-grade pay status shall not be less than an annual benefit payable monthly 
commencing on the first day of the calendar month coincident with or next 
following his Retirement equal to 35% of his Average Final Earnings, 
inclusive of his Other Retirement Income and his Basic Plan Benefit."

The Benefit of a Participant or Former Participant, whose employment is 
terminated other than by Retirement, disability, death, or following a 
Change of Control, shall be an annual benefit payable monthly commencing 
on the first day of the calendar month coincident with or next following 
his Normal Retirement Date, as determined under the preceding sentence 
but without taking into account the reduction factors, and if such Benefit 
is payable in a lump sum or annual installments pursuant to an election 
made in accordance with Section 4.6, payment thereof shall be made or 
commence on such Normal Retirement Date or on the first day of any month 
thereafter not later than the second anniversary of such Normal Retirement 
Date.

4.  SECTION 4.6 is hereby amended by deleting it in its entirety and 
replacing it with the following language to permit a lump sum payout upon 
termination of employment following a Change of Control:

            "The benefits under this Plan shall be payable to a Participant 
or Former Participant in the normal form such Participant's or Former 
Participant's retirement benefits would be payable under the Basic Plan 
determined solely on the basis of his marital status on his retirement 
benefit commencement date and without regard for any optional form of 
benefits elected under the Basic Plan.  Notwithstanding the preceding 
sentence, a Participant or Former Participant may elect that payment of any 
benefits under this Plan shall be made in accordance with any optional form 
of benefit available under the Basic Plan or as hereinafter provided in 
this Section 4.6.  A Participant or Former Participant may elect (the 
"Participant's Lump Sum Election") to receive payment of the actuarial 
equivalent of the aggregate of his benefits under this Plan and any 
Survivor's Benefit payable to his Surviving Spouse under this Plan in a 
lump sum (x) in cash on his Early Retirement Date, Normal Retirement Date, 
Deferred or Postponed Retirement Date, or Change of Control Termination 
Date, or the first day of any month thereafter not later than the first 
day of the month coincident with or next following the second anniversary 
of such Early Retirement Date, Normal Retirement Date, Deferred or 
Postponed Retirement Date, or Change of Control Termination Date, as the 
case may be, or on the fifth, tenth, fifteenth or twentieth anniversary 
of his Early Retirement Date, Normal Retirement Date, Deferred or 
Postponed Retirement Date, or Change of Control Termination Date, as the 
case may be, or (y) in two, three, four, five, ten, fifteen, or twenty 
equal annual cash installments commencing on his Early Retirement Date, 
Normal Retirement Date, Deferred or Postponed Retirement Date, or Change 
of Control Termination Date or the first day of any month thereafter not 
later than the first day of the month coincident with or next following 
the second anniversary of such Early Retirement Date, Normal Retirement 
Date, Deferred or Postponed Retirement Date, or Change of Control 
Termination Date, as the case may be.  If a Participant or a Former 
Participant terminates his employment by Retirement or following a 
Change of Control and dies with a Participant's 
Lump Sum Election in effect but prior to the payment of the full amount 
of such lump sum or annual installments, payment of the unpaid amount 
thereof shall be made to his Surviving Spouse, designated Beneficiary 
or estate in accordance with such Election.  Payment made in accordance 
with either of the two preceding sentences to the Participant or Former 
Participant, his Surviving Spouse, designated Beneficiary or estate 
shall constitute full and complete satisfaction of the Company's 
obligation in respect of the benefits of such Participant or Former 
Participant and any Survivor's benefit of his Surviving Spouse.  If a 
Participant or Former Participant dies before Retirement, the Company 
shall have no obligation in respect of his benefits under this Plan 
and shall be obligated to pay any Survivor's Benefit, if, but only if, 
his spouse shall survive him.  If the Participant or Former Participant 
does not make the Participant's Lump Sum Election, he may nevertheless 
elect (the "Survivor's Lump Sum Election") that if he should die prior 
to termination of employment, his Surviving Spouse shall receive the 
actuarial equivalent of her Survivor's Benefit, if any, in a lump sum 
(x) in cash on the Optional Survivor's Benefit Payment Date or the 
first day of any month thereafter not later than the first day of the 
month coincident with or next following the second anniversary of the 
Optional Survivor's Benefit Payment Date or on the fifth, tenth, 
fifteenth, or twentieth anniversary of the Optional Survivor's Benefit 
Payment Date, or (y) in two, three, four, five, ten, fifteen, or 
twenty equal annual cash installments commencing on the Optional 
Survivor's Benefit Payment Date or the first day of any month 
thereafter not later than the first day of the month coincident with 
or next following the second anniversary of the Optional Survivor's 
Benefit Payment Date.  A Participant or a Former Participant may 
make any election pursuant to this Section 4.6. or may modify or 
rescind such an election previously made:  (a), in the case of an 
election of a form of benefit other than a lump sum or annual 
installments pursuant to a Participant's Lump Sum Election or a 
Survivor's Lump Sum Election, at any time prior to the Participant's 
or Former Participant's Retirement or Change of Control Termination 
Date, except that in the case of a Participant or Former Participant 
whose employment is terminated other than by Retirement or following 
a Change of Control, such election, modification or rescission must 
be made at least 90 days prior to his Normal Retirement Date; (b), 
in the case of a Participant's Lump Sum Election by a Participant 
or a Former Participant whose Retirement occurs on or after October 
1, 1994, and on or before July 1, 1995, at least 30 days prior to 
the date of his Retirement;  (c), in the case of a Participant's 
Lump Sum Election by a Participant or a Former Participant who is 
not covered by clause (b) of this sentence, not later than the end 
of the calendar year preceding the calendar year in which the 
termination of his employment occurs and at least six months prior to 
such termination of employment; and (d), in the case of a Survivor's 
Lump Sum Election by a Participant of Former Participant, at least 
six months prior to his death; provided, however, that in the event 
of a Change of Control, a Participant or Former Participant may make 
a Participant's Lump Sum Election or a Survivor's Lump Sum Election, 
or modify or rescind such an Election previously made, within a period 
of 60 days following such Change of Control but in no event later than 
30 days prior to the date of the termination of his employment.  Any 
election pursuant to this Section 4.6, or any modification or rescission 
of a previous election, shall be made in writing and filed with the 
Committee before the applicable limitation of time specified in this 
Section 4.6, and any election purported to be filed after the applicable 
limitation of time shall be void.  Unless otherwise specified in the 
written form of election, the actuarial equivalent of the benefits 
payable to a Participant or a Former Participant who has made a 
Participant's Lump Sum Election, and the actuarial equivalent of any 
Survivor's Benefit payable to his Surviving Spouse pursuant to a 
Survivor's Lump Sum Election, shall be paid in five equal annual 
installments commencing on his Early Retirement Date, Normal Retirement 
Date, Deferred or Postponed Retirement Date, or Change of Control 
Termination Date, or the first day of the month coincident with or 
next following his death, as the case may be, with interest payable 
at the three-month U.S. Treasury bill rate as reported in The Wall 
Street Journal on the first business day of each calendar quarter.  
If benefits under this Plan are payable to a Participant or Former 
Participant in a different form than his retirement benefits under 
the Basic Plan, or if benefits under this Plan are payable to a 
Participant or Former Participant prior to his retirement benefits 
under the Basic Plan, the amount of the offset provided in this Plan 
for such Participant's or Former Participant's Basic Plan Benefit 
shall be actuarially converted into the form of benefit payable under 
this Plan but solely for purposes of calculating the amount of such offset.  
The amount of any lump sum payment shall be equal to the actuarial present 
value of the benefits payable under this Plan to a Participant, Former 
Participant or Surviving Spouse calculated as of the Early Retirement Date, 
Normal Retirement Date, Deferred or Postponed Retirement Date, Change of 
Control Termination Date or date of death of the Participant or Former 
Participant, as the case may be, by utilizing (a) the interest rate 
determined as of such Retirement Date, Change of Control Termination 
Date or date of death under the regulations of the Pension Benefit 
Guaranty Corporation for determining the present value of a lump sum 
distribution on plan termination that were in effect on September 1, 1993, 
and (b) the other applicable actuarial assumptions in use as of such 
Retirement Date, Change of Control Termination Date or date 
of death under the Basic Plan.  The amount of any annual installment 
shall be calculated by converting the benefits payable under this Plan 
to a Participant, Former Participant or Surviving Spouse, as the case 
may be, into a lump sum amount in accordance with the 
preceding sentence and by dividing such amount by the number of 
installments elected or deemed to have been elected by the Participant 
or Former Participant.  The amount of any lump sum or annual installment 
of the benefit of any Participant or Former Participant that is not paid 
within fifteen days after the date of his Retirement or Change of Control 
Termination Date, and the amount of any lump sum or annual installment of 
any Survivor's Benefit of his Surviving Spouse that is not paid within 
fifteen days after the Optional Survivor's Benefit Payment Date, shall bear 
interest from such fifteenth day after the date of Retirement, Change of 
Control Termination Date or the Optional Survivor's Benefit Payment Date, 
as the case may be, to but excluding the date of payment of such amount, 
at the Deferral Rate, compounded semi-annually.  Interest on any such 
amount shall be paid on the date such amount is paid or, at the election 
of the Participant or Former Participant, as the case may be, such interest 
shall be paid currently on a semiannual basis (with such election to be 
made on or before the last date on which a Participant's Lump Sum Election 
or Survivor's Lump Sum Election, as applicable, may be made).  If the 
benefits under this Plan are to continue after a Participant's or Former 
Participant's death for the benefit of his spouse or a designated 
beneficiary, then such Participant or Former Participant shall have the 
right at any time to change the recipient of the survivorship benefit 
payable under this Plan; provided, however, that any such change, if made 
after the applicable deadline set forth in the Basic Plan, shall not affect 
the amount of the benefit payable under this Plan as originally calculated 
or the term for which such benefit is payable, also as originally calculated.  
The Committee may, in its sole discretion, defer the payment of any lump 
sum or initial annual installment to a Participant or a Former Participant 
who is a "covered employee" as defined in Section 162(m) of the Internal 
Revenue Code of 1986, as amended, if such payment would be subject to such 
Section's limitation on deductibility; provided, however, that such payment 
shall not be deferred to a date later than the earliest date in the year in 
which such payment would not be subject to such limitation; and further
provided that the Company shall, at the time of payment of any amount so 
deferred, pay interest thereon from the due date thereof at              
the Deferral Rate, compounded semi-annually."


5.  Except as specified above, the SERP is hereby ratified and confirmed 
without amendment.