Exhibit 99.3


                  [LETTERHEAD OF CREDIT SUISSE FIRST BOSTON]


                                  Consent of
                                  ----------
                    Credit Suisse First Boston Corporation
                    --------------------------------------

Board of Directors
USX Corporation
600 Grant Street
Pittsburgh, PA 15219

Members of the Board:

     Reference is made to our opinion letter dated July 31, 2001 (our "Opinion")
with respect to the separation of the U.S. Steel Group and the Marathon Group of
USX Corporation ("USX") into two independent companies (the "Separation"). Our
opinion is for the information of the Board of Directors of USX in connection
with its consideration of such Separation and is not to be quoted or referred
to, in whole or in part, in any registration statement, prospectus or proxy
statement, or in any other document used in connection with the offering or sale
of securities, nor for any other purpose, without our prior written consent.

     In that regard, we hereby consent to the inclusion of our Opinion as Annex
B-1 to the proxy statement/prospectus of USX included in the Registration
Statement of United States Steel LLC on Form S-4 filed with the Securities and
Exchange Commission on September 20, 2001 (the "Registration Statement"),
relating to the Separation and references made to such Opinion in the
Registration Statement under the captions (i) Summary--Opinions of Financial
Advisors; (ii) Proposal One: The Separation--Background of the Separation; (iii)
Proposal One: The Separation--Factors Considered by the Board of Directors in
Approving the Separation and (iv) Proposal One: The Separation--Opinions of
Financial Advisors. In giving such consent, we do not admit that we come within
the category of persons whose consent is required under, nor do we admit that we
are "experts" for purposes of, the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.

CREDIT SUISSE FIRST BOSTON CORPORATION

/s/ Credit Suisse First Boston Corporation
__________________________________________
September 20, 2001