In order to elucidate receptors of proteolytic enzyme-treated red cells which react with Phaseolus coccineus L. lectin, the receptors prepared by affinity chromatography were serologically investigated. P. coccineus lectin had high agglutinin activity for bromelin-, papain- and pronase-treated red cells but that for the cells treated with ficin and trypsin was relatively low. Analyses of chemical composition revealed that sialic acid of the receptors from normal red cells was considerably much as compared with that from the treated cells. On the contrary, the enzyme treatment did not affect particularly carbohydrate composition of the receptors. Disc electrophoresis showed that the patterns of receptors from red cells treated with bromelin or papain were different from those from the other cells. On two-dimensional immunoelectrophoresis, the receptor of trypsin-treated cells gave five precipitation lines against anti-stroma and that of papain-treated cells three lines, but any other receptors showed no line. These findings indicate that there are plural receptors for P. coccineus lectin in red cells treated with each of proteolytic enzymes and that the receptors from respective red cells have electrophoretically and serologically different property.