Microorganisms that enantioselectively hydrolyze 1-cyanoalkyl acetates (aldehyde cyanohydrin) were screened. Candida tropicalis was found to be the best. The enzyme system of this strain catalyzed the enantioselective hydrolysis of (S)-isomers, leaving behind the (R)-acetates. The optical purities of recovered acetates were high as measured by 1H-NMR analysis in the presence of a chiral shift reagent.