Exhibit 16
                   Letter on change in certifying accountant.



                           BDO Seidman, LLP Letterhead

                         1700 Market Street, 29th Floor
                          Philadelphia, PA 19103-3962
                             Telephone 215-636-5500
                                Fax 215-636-5501


September 22, 2006

Securities and Exchange Commission
100 F Street N.E.
Washington, D.C. 20549




We have been  furnished  with a copy of the response to Item 4.01 of Form 8-KA-1
for the event that  occurred on  September  18,  2006 to be filed by  Hemispherx
Biopharma,  Inc.  We agree with the  statements  made in  response  to that Item
insofar as they relate to our Firm.


Very truly yours,

/s/ BDO Seidman, LLP
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BDO Seidman, LLP