A series of 2,2-disubstituted 1,3-oxathiolanes has been incubated with fungi known to be capable of efficient asymmetric oxidation of sulfides to sulfoxides. In three cases (2-phenyl-1,3-oxathiolane, 2-methyl-2-phenyl-1,3-oxathiolane, and 2-tert-butyl-2-phenyl-1,3-oxathiolane), sulfoxidation occurred to give a single diastereomer of sulfoxide, whose relative stereochemistry has been assigned by1H nuclear magnetic resonance analysis. The sulfoxides were obtained as racemates or had low enantiomeric enrichment. In some cases ketones, assumed to be formed by spontaneous hydrolysis of oxathiolane sulfoxides, were obtained, together with their reduction products, secondary alcohols.