Racemic diisophorone (500 mg) was converted by Cephalosporium aphidicola and Neurospora crassa over 10 days at 25 degrees C to 8 beta-hydroxydiisophorone in yields of 10% (52 mg) and 20% (103 mg), respectively. The structure was established by IR, specific rotation, mass spectral, 1D and 2D-NMR studies.