An enzyme with [alpha]-glucosidase activity isolated from barley malt and purified to some extent shows activity toward different substrates containing [alpha]-1,4- and [alpha]-1,6- glucosidic linkages, e.g. isomaltose, maltose, and panose. Heat inactivation, inhibition, and other experiments suggest that only 1 enzyme is involved in the hydrolysis of both types of linkages. Michaelis constants Km for iso-maltose, maltose, panose, isomaltotriose, and maltotriose were found to be 11, 2.0, 6.1, 25, and 2.4 m[image], respectively. Some inhibitor con-stants K1 are given, and the action of the enzyme preparation on phenyl [alpha]-D-glucoside, methyl [alpha]-D-glucoside, and sucrose is tested.