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                                                                       EXHIBIT 5


November 20, 2000




USG Corporation
125 South Franklin Street
Chicago, IL  60606-4678

         RE:      2,400,000 Shares of Common Stock
                  ($0.10 par value) and 2,400,000
                  Preferred Share Purchase Rights

Ladies and Gentlemen:

         I have acted as counsel for USG Corporation (the "Company") in
connection with the preparation and filing of a Registration Statement on Form
S-8 (the "Registration Statement") for the registration under the Securities Act
of 1933, as amended, of 2,400,000 shares of the Company's Common Stock, $0.10
par value (the "Common Stock"), which may be issued pursuant to the Company's
Omnibus Management Incentive Plan (the "Plan") and 2,400,000 Preferred Share
Purchase Rights which currently are attached to, and trade with, the Common
Stock.

         I have examined or considered:

         1.       A copy of the Company's Restated Certificate of Incorporation.

         2.       The By-laws of the Company.

         3.       Copies of resolutions duly adopted by the Board of Directors
                  of the Company relating to the Plan and to the Registration
                  Statement.

         4.       A copy of the Plan.


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USG Corporation
November 20, 2000
Page Two


         In addition to the examination outlined above, I have conferred with
various officers of the Company and have ascertained or verified, to my
satisfaction, such additional facts as I deemed necessary or appropriate for the
purposes of this opinion.

         Based upon the foregoing, I am of the opinion that:

                  (a)      The Company is a corporation duly organized, validly
                           existing and in good standing under the laws of the
                           State of Delaware.

                  (b)      All legal and corporate proceedings necessary for the
                           issuance of shares of Common Stock under the Plan
                           have been duly taken, and the Common Stock, upon
                           issuance pursuant to the terms of the Plan, and the
                           attached Preferred Share Purchase Rights, will be
                           duly authorized, legally and validly issued, fully
                           paid and non-assessable.

         I hereby consent to all references to me in the Registration Statement
and to the filing of this opinion by the Company as an Exhibit to the
Registration Statement.


Very truly yours,


/s/  Dean H. Goossen
--------------------
Dean H. Goossen