The antineoplastic substances isolated from Chamaenerium angustifolium, Chanerol, a macromolecular polyphenol, and its complex with polysaccharide, Chanerozan, have been studied in vitro in tests of haemagglutination, tumor cell agglutination, leucoagglutination and some others. The results obtained show Chanerol as a new phytohaemagglutinin (lectin) which has no group specificity for human erythrocytes (ABO system). As distinct from other lectins (proteins) Chanerol belongs to another chemical class (macromolecular polyphenols) and has no effect on lymphocytes in leukoagglutination and blast transformation tests. Both preparations have been shown capable of agglutinating tumor cells in vitro and revealed antitumor activity in the intravenous and intraperitoneal administration to mice with transplanted tumors. The toxicity of Chanerozan and its titre of human and mouse erythrocyte agglutination are considerably lower than those of Chanerol. Thus, judging by haemagglutination test Chanerozan behaves as a typical complex of agglutinin with concurrent sugar.