EXHIBIT 5.1
                  [LETTERHEAD OF SONNENSCHEIN NATH & ROSENTHAL]




November 5, 2001

Mediacom Broadband LLC
Mediacom Broadband Corporation
100 Crystal Run Road
Middletown, New York 10941

Ladies and Gentlemen:


         We have acted as counsel to Mediacom Broadband LLC, a Delaware limited
liability company ("Mediacom"), and Mediacom Broadband Corporation, a Delaware
corporation ("MBC" and, collectively with Mediacom, the "Issuers"), in
connection with the preparation and filing of the Issuers' registration
statement (the "Registration Statement") on Form S-4 (Registration Nos.
333-72440 and 333-72440-01), filed concurrently herewith with the Securities and
Exchange Commission ("SEC") under the Securities Act of 1933, as amended (the
"Securities Act"). The Registration Statement covers the registration of
$400,000,000 principal amount of 11% Senior Notes due 2013 of the Issuers (the
"Exchange Notes") to be offered in exchange for outstanding 11% Senior Notes due
2013 (the "Initial Notes"). The Exchange Notes will be issued under an indenture
relating to the Initial Notes and Exchange Notes (the "Indenture") among the
Issuers and The Bank of New York, as Trustee.


         In connection with rendering this opinion, we have examined and are
familiar with: (i) the limited liability company records of Mediacom, including
its organization documents, as amended to date, and minutes of meetings, or
written consents executed in lieu thereof, of its managing member; and (ii)
corporate records of MBC, including its organizational documents, as amended to
date, and minutes of meetings, or written consents executed in lieu thereof, of
its Board of Directors and sole shareholder.


         We have also examined such certificates of public officials,
certificates of officers of the Issuers and other records and documents as we
have deemed relevant and necessary for the purposes of the opinions herein
expressed.

         In making the aforesaid examinations, we have assumed the genuineness
of all signatures and the conformity to original documents of all copies
furnished to us as original or photostatic copies. We have also assumed that the
limited liability company and corporate records, as the case may be, furnished
to us by the Issuers include all limited liability company or corporate
proceedings taken by the Issuers to date.

         Based upon the foregoing and subject to the assumptions and
qualifications set forth herein, it is our opinion that when the Registration
Statement has become effective under the Securities Act of 1933, as amended, the
Exchange Notes have been duly executed and



Mediacom Broadband LLC
Mediacom Broadband Corporation
November 5, 2001
Page 2


authenticated in accordance with the Indenture, the Indenture has been qualified
under the Trust Indenture Act of 1939, as amended, the Initial Notes have been
validly tendered to the Issuers and the Exchange Notes have been delivered in
exchange therefor, the Exchange Notes will be validly issued and binding
obligations of the Issuers subject in each case to the effect of (i) Federal and
State bankruptcy, insolvency, reorganization, arrangement, moratorium,
fraudulent conveyance and other laws relating to or affecting the rights of
secured or unsecured creditors generally (or affecting the rights of only
creditors of specific types of debtors) and (ii) the application of general
principles of equity (regardless of whether enforcement is considered in
proceedings at law or in equity).

         The foregoing opinion is limited to the laws of the State of New York,
the laws of the United States of America and Delaware general corporation and
limited liability company laws and do not purport to express any opinion on the
laws of any other jurisdiction.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this firm and this opinion under
the heading "Legal Matters" in the prospectus comprising a part of such
Registration Statement and any amendment thereto. In giving such consent, we do
not hereby admit that we come within the category of persons whose consent is
required under Section 7 of the Securities Act or the rules and regulations of
the SEC thereunder.

         Except to the extent provided in the preceding paragraph, this opinion
is solely for your benefit and may not be furnished to, or relied upon by, any
other person or entity without the express prior written consent of the
undersigned. This opinion is limited to the matters set forth herein; no opinion
may be inferred or implied beyond the matters expressly stated in this letter.

                                              Very truly yours,

                                              SONNENSCHEIN NATH & ROSENTHAL


                                                      /s/  Ira I. Roxland
                                              By:_______________________________
                                                      A Member of the Firm