High titre antiserum was obtained by immunization of rabbits with phalacidine-concanavaline A. Specific antiphalacidine antibodies were isolated from this serum on immobilized phalacidine. It was established by testing with antirabbit globulin sera that these antibodies were of IgG class only. IgG fraction was isolated from the immune serum by ion-exchange chromatography, but specific antibodies, which represented 8% of IgG of the serum, were isolated from it by affinity chromatography. The antibodies isolated by affinity, were tested against other phalatoxines and amotoxines. The results showed that they reacted with phalatoxines, but not with amatoxines and could be used in tests for quantitative determination of phalatoxines in mushroom extracts and body fluids.