EXHIBIT 4 SCHERING-PLOUGH CORPORATION AMENDMENT TO BY-LAWS Effective September 22, 1998, pursuant to a resolution of the Board of Directors, the By-laws of Schering-Plough Corporation have been amended as follows: 1. By deleting the second, third and fourth sentences of the second paragraph of Section 2 of Article III and replacing such sentences with the following: "For business to be properly brought before an annual meeting by a shareholder, the shareholder must have given timely notice thereof in writing to the Secretary of the Corporation and such business must otherwise be a proper matter for shareholder action. To be timely, a shareholder's notice shall be delivered to the Secretary at the principal executive offices of the Corporation not later than the close of business on the 90th day nor earlier than the close of business on the 120th day prior to the first anniversary of the preceding year's annual meeting; provided, however, that in the event that the date of the annual meeting is more than 30 days before or more than 60 days after such anniversary date, notice by the shareholder to be timely must be so delivered not earlier than the close of business on the 120th day prior to such annual meeting and not later than the close of business on the later of the 90th day prior to such annual meeting or the 10th day following the day on which public announcement of the date of such meeting is first made by the Corporation. In no event shall the public announcement of an adjournment of an annual meeting commence a new time period for the giving of a shareholder's notice as described above. Such shareholder's notice shall set forth (a) as to any business that the shareholder proposes to bring before the meeting, a brief description of the business desired to be brought before the meeting, the reasons for conducting such business at the meeting and any material interest in such business of such shareholder and the beneficial owner, if any, on whose behalf the proposal is made; and (b) as to the shareholder giving the notice and the beneficial owner, if any, on whose behalf the nomination or proposal is made (i) the name and address of such shareholder as they appear on the Corporation's books, and of such beneficial owner and (ii) the class and number of shares of the Corporation which are owned beneficially and of record by such shareholder and such beneficial owner." 2. By deleting the phrase "by oral telegraph and written notice given to each director not less than forty-eight hours before such meeting" from Section 5 of Article V and replacing such phrase with the following: "Notice of any special meeting of directors shall be given to each director at his business or residence in writing by hand delivery, first-class or overnight mail or courier service, telegram or facsimile transmission, or orally by telephone. If mailed by first-class mail, such notice shall be deemed adequately delivered when deposited in the United States mails so addressed, with postage thereon prepaid, at least five (5) days before such meeting. If by telegram, overnight mail or courier service, such notice shall be deemed adequately delivered when the telegram is delivered to the telegraph company or the notice is delivered to the overnight mail or courier service company at least twenty-four (24) hours before such meeting. If by facsimile transmission, such notice shall be deemed adequately delivered when the notice is transmitted at least twelve (12) hours before such meeting. If by telephone or by hand delivery, the notice shall be given at least twelve (12) hours prior to the time set for the meeting. A meeting may be held at any time without notice if all the directors are present or if those not present waive notice of the meeting. Members of the Board of Directors, or any committee thereof, may participate in a meeting of the Board of Directors or such committee by means of conference telephone or similar communications equipment by means of which all persons participating in the meeting can hear each other, and such participation in a meeting shall constitute presence in person at such meeting.