Three amylases were purified to electrophoretic homogeneity from viscera of hard clam Meretrix lusoria by ammonium sulfate fractionation, Sepharose 6B, DEAE-Sephadex A-50, Sephadex G-200 and PBE 94 chromatographies. The purified amylases had molecular masses of 49.6, 58.7 and 100 kDa and were designated AI-1, AI-2 and AII, respectively. Both AI-1 and AI-2 could digest amylose into glucose and maltose, while AII could digest amylose and pullulan into glucose. The optimal pH and temperatures for AI-1, AI-2 and AII were 7.0, 7.5 and 7.5, and 40, 50 and 50 ∞ C, respectively. According to the substrate specificity, the purified AI-1 and AI-2 were considered to be multifunctional exo-and endo-types of a -amylase-like enzymes, while AII was exo-type g -amylase-like enzyme. They were Ca 2 + -independent enzymes.