4β,19-Dihydroxyandrost-5-en-17-one (6) is an excellent competitive inhibitor of estrogen synthetase (aromatase). Alternate, improved synthesis of this inhibitor was established. Treatment of 19-(tert-butyldimethylsilyloxy)androst-4-en-17-one (8) with m-chloroperbenzoic acid gave a 1.4 : 1 mixture of 4α,5α-epoxide 9 and its 4β,5β-isomer 10. The mixture was reacted with dil. HClO₄ in dioxane to produce principally 4β,5α-diol 11 (80%) of which acetylation followed by dehydration with SOCl₂ yielded 4β,19-diacetoxy-5-ene compound 14 in good yield. Alkaline hydrolysis of diacetate 14 gave 4β,19-diol 6. The minimum energy conformation of the powerfull aromatase inhibitor 6 was obtained with the PM3 method and compared with that of the structurally related diol steroid, 4-ene-5β,19-diol 3, a weak competitive inhibitor.