EXHIBIT 5.1


                       [LETTERHEAD OF COMCAST CORPORATION]


                                                     December 23, 2002


Comcast Corporation
1500 Market Street
Philadelphia, Pennsylvania 19102-2148


Ladies and Gentlemen:

     I am Senior Vice President, General Counsel and Secretary of Comcast
Corporation, a Pennsylvania corporation (the "Company") and have acted for the
Company in connection with the Company's Registration Statement on Form S-3 (the
"Registration Statement") (File No. 333-101861) filed with the Securities and
Exchange Commission pursuant to the Securities Act of 1933, as amended, for the
registration of the sale by the Company from time to time of up to
$10,000,000,000 aggregate principal amount of (i) senior debt securities and
subordinated debt securities (together, the "Debt Securities"), that shall be
fully and unconditionally guaranteed by each of Comcast Cable Communications,
Inc., Comcast Cable Communications Holdings, Inc., Comcast Cable Holdings, LLC
and Comcast MO Group, Inc. (together, the "Cable Guarantors"), (ii) shares of
preferred stock, without par value (the "Preferred Stock"), (iii) shares of
Class A Common Stock, $0.01 par value (the "Class A Common Stock"), (iv) shares
of Class A Special Common Stock, $0.01 par value (the "Class A Special Common
Stock"), (v) warrants to purchase Debt Securities, Preferred Stock, Class A
Common Stock, Class A Special Common Stock or other securities or rights (the
"Warrants"), (vi) purchase contracts (the "Purchase Contracts") requiring the
holders thereof to purchase or sell (A) the Company's securities or securities
of an entity unaffiliated or affiliated with the Company, a basket of such
securities, an index or indices of such securities or any combination of the
above, (B) currencies or composite currencies or (C) commodities, (vii) units
(the "Units") consisting of Debt Securities, Warrants, Purchase Contracts,
Preferred Stock, Class A Common Stock or Class A Special Common Stock or any
combination of the foregoing,




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(viii) guarantees (the "Cable Guarantees") of the Debt Securities by the Cable
Guarantors and (ix) guarantees (the "Additional Guarantees") of Warrants,
Purchase Contracts and Units or any combination of the foregoing by the Cable
Guarantors. The Debt Securities, Preferred Stock, Class A Common Stock, Class A
Special Common Stock, Warrants, Purchase Contracts, Units, Cable Guarantees and
Additional Guarantees are herein collectively referred to as the "Securities".
The Debt Securities and the Preferred Stock may be convertible and/or
exchangeable for Securities or other securities or rights. The senior Debt
Securities are to be issued pursuant to an Indenture (the "Senior Indenture")
among the Company, the Cable Guarantors and The Bank of New York, as Trustee,
substantially in the form attached as an exhibit to the Registration Statement.
The subordinated Debt Securities are to be issued pursuant to an Indenture (the
"Subordinated Indenture") among the Company, the Cable Guarantors and The Bank
of New York, as Trustee, substantially in the form attached as an exhibit to the
Registration Statement. The Senior Indenture and the Subordinated Indenture are
hereinafter referred to individually as an "Indenture" and collectively as the
"Indentures". The Company may offer Depositary Shares (the "Depositary Shares")
representing interests in Preferred Stock deposited with a Depositary and
evidenced by Depositary Receipts, and such Depositary Shares are also covered by
the Registration Statement.

     I have examined originals or copies, certified or otherwise identified to
my satisfaction, of such documents, corporate records, certificates of public
officials and other instruments as I have deemed necessary or advisable for the
purpose of rendering this opinion.

     1. Upon designation of the preferences and relative, participating,
optional and other special rights, and qualifications, limitations or
restrictions, of any series of Preferred Stock by the Board of Directors of the
Company and proper filing with the Secretary of State of the Commonwealth of
Pennsylvania of a Certificate of Designations relating to such series of
Preferred Stock, all necessary corporate action on the part of the Company will
have been taken to authorize the issuance and sale of such series of Preferred
Stock proposed to be sold by the Company, and when such shares of Preferred
Stock are issued and delivered against payment therefor in accordance with the
applicable underwriting or other agreement or upon conversion in accordance with
the terms of any other Security that has been duly authorized, issued, paid for
and delivered, such shares will be validly issued, fully paid and
non-assessable.

     2. When the specific terms of any offering or offerings of Class A Special
Common Stock have been duly established by the Board of Directors of the Company
and in accordance with provisions of any applicable underwriting





Comcast Corporation                    3                       December 23, 2002


agreement so as not to violate any applicable law or agreement or instrument
then binding on the Company, and shares of the Class A Special Common Stock have
been issued and sold against payment therefor in accordance with the applicable
underwriting or other agreement or upon exchange in accordance with the terms of
any Security that has been duly authorized, issued, paid for and delivered, such
shares will be validly issued, fully paid and nonassessable.

     3. When the specific terms of any offering or offerings of Class A Common
Stock have been duly established by the Board of Directors of the Company and in
accordance with provisions of any applicable underwriting agreement so as not to
violate any applicable law or agreement or instrument then binding on the
Company, and shares of the Class A Common Stock have been issued and sold
against payment therefor in accordance with the applicable underwriting or other
agreement or upon exchange in accordance with the terms of any other Security
that has been duly authorized, issued, paid for and delivered, such shares will
be validly issued, fully paid and non-assessable.

     4. When Depositary Shares evidenced by Depositary Receipts are issued and
delivered in accordance with the terms of a Deposit Agreement against the
deposit of duly authorized, validly issued, fully paid and non-assessable shares
of Preferred Stock, such Depositary Shares will entitle the holders thereof to
the rights specified in the Deposit Agreement.

     In connection with my opinions expressed above, I have assumed that, at or
prior to the time of the delivery of any such Security, (i) the Board of
Directors shall have duly established the terms of such Security, (ii) the
Registration Statement shall have been declared effective and such effectiveness
shall not have been terminated or rescinded and (iii) there shall not have
occurred any change in law affecting the validity or enforceability of such
Security. I have also assumed that none of the terms of any Security to be
established subsequent to the date hereof, nor the issuance and delivery of such
Security, nor the compliance by the Company with the terms of such Security will
violate any applicable law or will result in a violation of any provision of any
instrument or agreement then binding upon the Company, or any restriction
imposed by any court or governmental body having jurisdiction over the Company.

     I am a member of the Bar of the Commonwealth of Pennsylvania and the
foregoing opinion is limited to the laws of the Commonwealth of Pennsylvania and
the federal laws of the United States of America.

     I hereby consent to the filing of this opinion as an exhibit to the
Registration Statement. In addition, I consent to the reference to me under the
caption "Legal Matters" in the prospectus.



Comcast Corporation                    4                       December 23, 2002


     This opinion is rendered solely to you in connection with the above matter.
This opinion may not be relied upon by you for any other purpose or relied upon
by or furnished to any other person without my prior written consent.



                                              Very truly yours,

                                              /s/ Arthur R. Block