AbstractA strain ofAphanocladiumalbum reduces the C‐3 carbonyl group in testosterone or androstendione to to 3α‐allyl alcohol. In some derivatives of these steroids the same carbonyl group is reduced to allyl alcohol with stereospecificity, depending on whether chlorine at C‐4 or a 17α‐methyl group is present. On the other hand, the presence of C‐4 methyl group, a C‐19 hydroxy group, a C‐17 acetyl one, or a double bond conjugated with the 4‐en‐3‐ ketone system totally inhibits the formation of allyl alcohols at C‐3.At the samé time, the C‐17 carbonyl group in androstendione or in its derivatives is reduced to a respective 17β‐alcohol.In the derivatives with an additional 2‐exomethylene group the doubl