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                                                                     EXHIBIT 5.1



                        [Letterhead of Alston & Bird LLP]

M. Hill Jeffries                                      Direct Dial (404) 881-7823
                                 August 6, 1999


CytRx Corporation
154 Technology Parkway
Norcross, Georgia 30092

         Re:               Registration Statement on Form S-8

Ladies and Gentlemen:

         We have acted as counsel to CytRx Corporation, a Delaware corporation
("the Company"), in connection with the filing of the above-referenced
Registration Statement (the "Registration Statement"), with the Securities and
Exchange Commission (the "Commission") to register under the Securities Act of
1933, as amended (the "Securities Act"), up to 500,000 shares (the "Shares") of
the Company's Common Stock, par value $.001 per share (the "Common Stock"),
which may be issued by the Company upon the grant or exercise of awards pursuant
to the CytRx Corporation 1998 Long-Term Incentive Plan (the "Plan"). This
opinion letter is rendered pursuant to Item 8 of Form S-8 and Item 601(b)(5) of
the Commission's Regulation S-K.

         We have examined the Certificate of Incorporation of the Company, as
amended, the Bylaws of the Company, as amended, records of proceedings of the
Board of Directors and stockholders of the Company deemed by us to be relevant
to this opinion letter, the Plan and the Registration Statement. We also have
made such further legal and factual examinations and investigations as we deemed
necessary for purposes of expressing the opinion set forth herein.

         As to certain factual matters relevant to this opinion letter, we have
relied upon certificates and statements of officers of the Company and
certificates of public officials. Except to the extent expressly set forth
herein, we have made no independent investigations with regard thereto, and
accordingly, we do not express any opinion as to matters that might have been
disclosed by independent verification.

         This opinion letter is provided to the Company and the Commission for
their use solely in connection with the transactions contemplated by the
Registration Statement and may not be used, circulated, quoted or otherwise
relied upon by any other person or for any other purpose without our express
written consent. The only opinion rendered by us consists of those matters set
forth in the sixth paragraph hereof, and no opinion may be implied or inferred
beyond those expressly stated.

         Our opinion set forth below is limited to the laws of the State of
Delaware, and we do not express any opinion herein concerning any other laws.


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         Based upon the foregoing, it is our opinion that the Shares to be
issued under the Plan are duly authorized and, when issued by the Company in
accordance with the terms of the Plan, will be validly issued, fully paid and
nonassessable.

         We consent to the filing of this opinion as an exhibit to the
Registration Statement. In giving such consent, we do not thereby admit that we
are within the category of persons whose consent is required under Section 7 of
the Securities Act or the rules and regulations of the Commission thereunder.

                                            ALSTON & BIRD LLP


                                            By: /s/ M. Hill Jeffries
                                                --------------------------------
                                                M. Hill Jeffries, Partner