March 7, 1997


Board of Directors
Aronex Pharmaceuticals, Inc.
3400 Research Forest Drive
The Woodlands, Texas  77381

Gentlemen:

We have acted as counsel to Aronex  Pharmaceuticals,  Inc.  (the  "Company")  in
connection  with  the  Company's   Registration   Statement  on  Form  S-3  (the
"Registration  Statement") relating to the registration under the Securities Act
of 1993, as amended (the "Securities Act"), of the offer and sale by the Selling
Stockholders  identified in the  Registration  Statement of up to 570,273 shares
(the  "Shares")  of the  Company's  Common  Stock,  par value  $0.001  per share
("Common Stock").

As the basis for the  opinions  hereinafter  expressed,  we have  examined  such
statutes,  regulations,   corporate  records  and  documents,   certificates  of
corporate  and  public  officials,  and  other  instruments  as we  have  deemed
necessary or advisable.  In such examination we have assumed the authenticity of
all documents  submitted to us as originals and the conformity with the original
documents of all documents submitted to us as copies.

Based on the foregoing and on such legal considerations as we deem relevant,  we
are of the  opinion  that the Shares have been duly  authorized  and are validly
issued, fully paid and nonassessable.

We hereby  consent to the use of this opinion as an exhibit to the  Registration
Statement  and  reference to our firm under the caption  "Legal  Matters" in the
Prospectus included therein.



                                            Very truly yours,


                                            /s/ ANDREWS & KURTH L.L.P.



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