EXHIBIT 5
 
                               [SIDLEY & AUSTIN]
 
                                 July 30, 1997
 
United States Cellular Corporation
8410 West Bryn Mawr Avenue
Suite 700
Chicago, Illinois 60631
 
         Re: $400,000,000 Principal Amount of Debt Securities
 
Ladies and Gentlemen:
 
    We refer to the Registration Statement on Form S-3 (the "Registration
Statement") being filed by United States Cellular Corporation, a Delaware
corporation (the "Company"), with the Securities and Exchange Commission (the
"SEC") under the Securities Act of 1933, as amended (the "Securities Act"),
relating to the shelf registration of $400,000,000 principal amount of the
Company's debt securities (the "Debt Securities"). The Debt Securities are to be
issued under an Indenture to be dated as of August   , 1997 between the Company
and The First National Bank of Chicago, as trustee (the "Trustee").
 
    We are familiar with the proceedings to date with respect to the proposed
issuance and sale of the Debt Securities and have examined such records,
documents and questions of law, and satisfied ourselves as to such matters of
fact, as we have considered relevant and necessary as a basis for this opinion.
 
    Based on the foregoing, we are of the opinion that:
 
    1.  The Company is duly incorporated and validly existing under the laws of
the State of Delaware.
 
    2.  The Company has corporate power and authority to execute and deliver the
Indenture and to authorize and sell the Debt Securities.
 
    3.  Each series of Debt Securities will be legally issued and binding
obligations of the Company (except to the extent enforceability may be limited
by applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent
transfer or other similar laws affecting the enforcement of creditors' rights
generally and by the effect of general principles of equity, regardless of
whether enforceability is considered in a proceeding in equity or at law) when
(i) the Registration Statement, as finally amended (including any necessary
post-effective amendments), shall have become effective under the Securities Act
and the Indenture (including any necessary supplemental indenture) shall have
been qualified under the Trust Indenture Act of 1939, as amended, and duly
executed and delivered by the Company and the Trustee; (ii) a Prospectus
Supplement with respect to such series of Debt Securities shall have been filed
(or transmitted for filing) with the SEC pursuant to Rule 424 under the
Securities Act; (iii) the Company's Board of Directors or a duly authorized
committee thereof shall have duly adopted final resolutions authorizing the
issuance and sale of such series of Debt Securities as contemplated by the
Registration Statement and the Indenture; and (iv) such series of Debt
Securities shall have been duly executed and authenticated as provided in the
Indenture and such resolutions and shall have been duly delivered to the
purchasers thereof against payment of the agreed consideration therefor.
 
    For the purposes of this opinion, we have assumed that there will be no
changes in the laws currently applicable to the Company and that such laws will
be the only laws applicable to the Company.
 
    We do not find it necessary for the purposes of this opinion to cover, and
accordingly we express no opinion as to, the application of the securities or
blue sky laws of the various states to sales of the Debt Securities.

    This opinion is limited to the Securities Act, the laws of the State of
Illinois and the Delaware General Corporation Law.
 
    The Company is controlled by Telephone and Data Systems, Inc. ("TDS") and
TDS is controlled by a voting trust. Walter C.D. Carlson, a trustee and
beneficiary of the voting trust and a director of TDS, the Company and certain
other subsidiaries of TDS, Michael G. Hron, the Secretary of TDS and certain
subsidiaries of TDS, William S. DeCarlo, the Assistant Secretary of TDS and
certain subsidiaries of TDS, Stephen P. Fitzell, the Secretary of the Company
and certain other subsidiaries of TDS, and Sherry S. Treston, the Assistant
Secretary of the Company and certain other subsidiaries of TDS, are partners of
this Firm.
 
    We hereby consent to the filing of this opinion as an Exhibit to the
Registration Statement and to all references to our Firm included in or made a
part of the Registration Statement.
 
                                          Very truly yours,
                                          /s/ SIDLEY & AUSTIN