Three new lectins, MLA-I, MLA-II and MLA-III, have been isolatedand purified from the hemolymph of Meretrix lusoria and reported previously. Biophysicochemical characteristics were investigated with these three MLA lectins. The MLA lectins agglutinated human erythrocytes non specifically and proved as D-galactose group carbohydrate specific. Molecular weight of ML.A-I. II and III were estimated to be 330, 500 and 310KD, respectively, by gel filtration on Sepharose CL-6B column. On SDS-polyacrylamide gel electrophoresis, ML.A-I was dissociated into a single subunit of 42KD, MLA-II was into the twelve subunits of 46, 32, 30, 28, 25, 23. 22, 20. 19, 16, 15, and 14KD, and MLA-III was into the two subunits of 72 and 44KD. The pl of MLA-I, II, III were 4.0. 4.9 and 5.0. Amino acid analysis revealed a high contents of acidic and hydroxy amino acids, and a paucity of sulfur containing amino acids. Proline was not contained in MLA-II.