EXHIBIT 5.1



                                   SIDLEY & AUSTIN
                               ONE FIRST NATIONAL PLAZA
                               CHICAGO, ILLINOIS  60603
                                    (312) 853-7000


                                   March 23, 1998


Telephone and Data Systems, Inc.
Suite 4000
30 North LaSalle Street
Chicago, Illinois  60602


          Re:    TELEPHONE AND DATA SYSTEMS, INC. REGISTRATION STATEMENT ON
                 FORM S-3

Gentlemen:

          We are counsel to Telephone and Data Systems, Inc., a Delaware
corporation (the "Company"), and have represented the Company in connection with
the Form S-3 Registration Statement (the "Registration Statement") being filed
by the Company with the Securities and Exchange Commission under the Securities
Act of 1933, as amended (the "Securities Act"), with  respect to the
registration of TDS Telecommunications Group Common Shares of the Company, par
value $0.01 per share (the "Telecom Group Shares"), to be issued and sold
pursuant to the proposed public offering by the Company of Telecom Group Shares.

          In rendering this opinion, we have examined and relied upon a copy of
the Registration Statement, the Prospectus included therein, the Certificate of
Incorporation of the Company, as filed with the Secretary of State of Delaware
on December 12, 1997, the form of Restated Certificate of Incorporation of the
Company expected to be filed with the Secretary of State of Delaware prior to
the offering of the Telecom Group Shares and the form of the Underwriting
Agreement to be entered into by and among the Company and Smith Barney Inc.
and Credit Suisse First Boston Corporation, as representatives of the several
underwriters (the "Underwriting Agreement").  We have also examined and relied
upon originals, or copies of originals certified to our satisfaction, of such
agreements, documents, certificates and other statements of governmental
officials and other instruments, have examined such questions of law and have
satisfied ourselves as to such matters of fact as we have considered relevant
and necessary as a basis for this opinion.  We have assumed the authenticity of
all documents submitted to us as originals, the genuineness of all signatures,
the legal capacity of all natural persons and the conformity with the original
documents of any copies thereof submitted to us for our examination.  We have
also assumed the consummation of the merger of Telephone and Data Systems, Inc.,
an Iowa corporation, with and into the Company as described in that certain
Registration Statement on Form S-4 (No. 333-42535), with the Company surviving
such merger, and the related restatement of the Certificate of Incorporation of
the Company pursuant to such merger.

          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.     Each of the Telecom Group Shares to be issued pursuant to the
Underwriting Agreement and registered pursuant to the Registration Statement has
been duly authorized and will be validly issued, fully paid and nonassessable
when (i) the Registration Statement, as finally amended, shall have become
effective under the Securities Act; (ii) the Company's Board of Directors or a
duly authorized committee thereof shall have duly adopted final resolutions
authorizing the issuance and sale of shares of the Telecom Group Shares as
contemplated by the Registration Statement; and (iii) certificates representing
the Telecom Group Shares have been duly executed, countersigned, registered and
duly 



Telephone and Data Systems, Inc.
March 23, 1998
Page 2


delivered to the purchasers thereof against payment of the agreed consideration
therefor in accordance with such resolutions, the Underwriting Agreement and the
Registration Statement.

          The foregoing opinions are limited to the Securities Act and the
General Corporation Law of the State of Delaware.  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 the issuance of Telecom Group Shares.

          The Company is controlled by a voting trust.  Walter C.D. Carlson, a
trustee and beneficiary of the voting trust and a director of the Company and
certain subsidiaries of the Company, Michael G. Hron, the Secretary of the
Company and certain subsidiaries of the Company, William S. DeCarlo, the
Assistant Secretary of the Company and certain subsidiaries of the Company,
Stephen P. Fitzell, the Secretary of certain subsidiaries of the Company, and
Sherry S. Treston, the Assistant Secretary of certain subsidiaries of the
Company, 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 in or made a part of
the Registration Statement.

                                        Very truly yours,



                                        SIDLEY & AUSTIN