6α- and 6β-Hydroxytestolactone were prepared by microbiological transformation of 3β-hydroxy- d -homo-17a-oxa-androstan-17-on-5α, 6α- or 5β,6β-epoxide with Flavobacterium dehydrogenans . Using Arthobacter simplex and the same substrates, the two corresponding 1,2-dehydrotestolactones were formed, whereas Bacillus lentus yielded only the 6α-hydroxy-1-dehydrotestolactone. The starting materials were prepared from 3β-hydroxy-5-androstene-17-on.