Abstract S-methyl β-hydroxysulfoxides of fairly high optical purity (up to 80%) may be prepared by direct asymmetric oxidation [Bu t O 2 H, Ti (OPr i) 4,(+)-DET] of acetylated or silylated S-methyl β-hydroxysulfides and subsequent deprotection. The upgrading of the optical purity from 78% up to> 98% by simple crystallization has been obtained.