1. Partially O-methylated amyloses were prepared by Haworth's methylation of amylose and the action of Taka-amylase A [EC 3.2.1.1] on them was examined. 2. Evidence was obtained indicating that the glucosidic bonds of methylated amyloses were hydrolyzed by Taka-amylase A, but the 2-O-and 6-O-methyl-glucosidic bonds were not attacked. 3. 6-O-Methyl-glucosyl-glucose was isolated from the digest, suggesting that a glucosidic bond adjacent to a 6-O-methyl-glucosyl residue was hydrolyzed by Taka-amylase A. 4. A greater influence by 2-O-methylation than 6-O-methylation on the susceptibility of the substrate was observed.