A highly selective hydrogenation of 3-keto in steroids to 3-hydroxyl steroids catalyzed by hydroxysteroid dehydrogenases (HSDHs) was demonstrated. The Ct3α-HSDH-catalyzed hydrogenation generated 3α-hydroxyl steroids as the main enantiopure isomers in high yields, while the Ss3β-HSDH catalytic system afforded 3β-hydroxyl steroids in excellent yields. In both catalytic systems, the hydrogenation proceeded