EXHIBIT 5.1

                                  CD Radio Inc.
                           1180 Avenue of the Americas
                               New York, NY 10036

                                                                 October 7, 1998


CD Radio Inc.
1180 Avenue of the Americas
New York, NY 10036


Dear Sirs:

         I am familiar with the CD Radio 401(k) Savings Plan (the "Plan") under
which 50,000 shares of common stock, par value $.001 per share, of CD Radio
Inc., a Delaware corporation (the "Company"), have been authorized initially for
issuance (the "Shares"). I have acted as counsel to the Company in connection
with the preparation and filing with the Securities and Exchange Commission
under the Securities Act of 1933, as amended (the "Act"), of a Registration
Statement on Form S-8 (the "Registration Statement") with respect to the
registration under the Act of the Shares and 50,000 Preferred Stock Purchase
Rights (the "Rights"), which are appurtenant to, and trade with, the Shares. In
this connection, I have examined such records, documents and proceedings, as I
have deemed relevant and necessary as a basis for the opinion expressed herein.

         Based upon the foregoing, I am of the opinion that Shares have been
duly authorized for issuance under the Plan by all proper corporate action and,
when such Shares have been issued pursuant to the provisions of the Plan as set
forth in the Registration Statement, and any conditions or restrictions relating
thereto shall have been satisfied, such Shares will be legally issued, fully
paid and non-assessable. When the Rights are issued in accordance with the terms
of the Plan and the Rights Agreement between the Company and Continental Stock
Transfer & Trust Company, as Rights Agent, the Rights will be duly and validly
issued.

         I hereby consent to the filing of this opinion as an Exhibit to the
Registration Statement.


                                                   Very truly yours,


                                                   /s/ Patrick L. Donnelly
                                                   -----------------------
                                                   Patrick L. Donnelly
                                                   Executive Vice President,
                                                   General Counsel and Secretary