A simple and convenient method for purification of the epidithiodioxopiperazine mycotoxin sporidesmin A from crude extracts of Pithomyces chartarum has been developed. The method involves reduction of sporidesmin to the water-soluble dithiol using NaBH4, followed by removal of lipophilic contaminants by liquid-liquid partition. The dithiol is then oxidized back to the lipophilic sporidesmin A, which is then extracted, purified by flash chromatography, and crystallized from CHCl3 to give the pure material as the chloroform solvate in overall yields of 44-63 %. The method may be applicable to purification of other dithiodioxopiperazines by judicious choice of reducing and oxidizing agents. The published 13C NMR assignments of some of the quaternary resonances of sporidesmin A are revised as a result of a series of one- and two-dimensional NMR experiments which allowed unambiguous assignment of the 1H and 13C resonances.