Regioselective ethanolysis of peracylated methyl beta, alpha-D-glucopyranoside and methyl alpha-D-mannopyranoside in anhydrous organic solvent (n-hexane/EtOH = 99/1) could afford 6-OH derivatives exclusively by Candida rugosa lipase (CPL). No 4 --> 6 acyl migration was observed in such an anhydrous solvent system. Substrates with propanoyl groups were more reactive than with acetyl groups on CRL-catalyzed reactions.