EXHIBIT 15

OCTOBER 28, 2005
TO THE SHAREHOLDERS AND BOARD OF DIRECTORS OF SCHERING-PLOUGH CORPORATION:

     We have made a review, in accordance with the standards of the Public
Company Accounting Oversight Board (United States), of the unaudited interim
financial information of Schering-Plough Corporation and subsidiaries for the
periods ended September 30, 2005 and 2004, as indicated in our report dated
October 28, 2005; because we did not perform an audit, we expressed no opinion
on that information.

     We are aware that our report referred to above, which is included in your
Quarterly Report on Form 10-Q for the quarter ended September 30, 2005, is
incorporated by reference in Registration Statements No. 2-83963, No. 33-50606,
No. 333-30331, No. 333-87077, No. 333-91440, No. 333-104714, No. 333-105567, No.
333-105568, No. 333-112421 and No. 333-121089 on Form S-8, Post Effective
Amendment No. 1 to Registration Statement No. 2-84723 on Form S-8, Post
Effective Amendment No. 1 to Registration Statement No. 333-105567 on Form S-8,
and Registration Statements No. 333-12909, No. 333-853, No. 333-30355, and No.
333-113222 on Form S-3.

     We also are aware that the aforementioned report, pursuant to Rule 436(c)
under the Securities Act of 1933, is not considered a part of the Registration
Statements prepared or certified by an accountant or a report prepared or
certified by an accountant within the meaning of Sections 7 and 11 of that Act.

/s/ Deloitte & Touche LLP

Parsippany, New Jersey