Microbial metabolism of danazol (17alpha-pregna-2,4-dien-20-yno[2,3-d]isoxazol-17beta-ol) by Beauveria bassiana ATCC 7159 and Glyocladium viride ATCC 10097 afforded four metabolites. The isolated metabolites were identified by different spectroscopic techniques as 6beta-hydroxy danazol, which is a not yet reported danazol metabolite, 17beta-hydroxy-17alpha-pregn-4-en-20-yn-3-one (ethisterone) and 17beta-hydroxy-2alpha-(hydroxymethyl)-17alpha-pregn-4-en-20-yn-3-one (2alpha-hydroxymethyl ethisterone), which represent the major danazol metabolites detected in human urine. The last metabolite, 6beta,17beta-dihydroxy-2-(hydroxymethyl)-17alpha-pregna-1,4-dien-20-yn-3-one, is also a minor human metabolite, for which the NMR data are described here for the first time. The metabolites were isolated in quantities that allowed their use for direct comparison in routine doping analysis.