The seeds of winged bean, Psophocarpus tetragonolobus (L.) DC, contain a group of acidic lectins (pI ≊ 5.5) and a group of basic lectins (pI < 9.5) characterised by different erythrocyte hemagglutinating specificities. Three basic lectins were separated and purified to apparent homogeneity by chromatography on Ultrogel AcA44 and SP-Sephadex C-25. These lectins are glycoproteins with relative molecular mass of 58000. The total carbohydrate content of the major lectins, B2 and B3, was 5% and was comprised of mannose, N-acetylglucosamine, fucose and xylose in amounts corresponding to 9, 8, 8 and 3 mol/58000g, respectively, for both lectins. Electrophoresis in dodecyl sulfate gave a single subunit of relative molecular mass 29000 for each lectin. Isoelectric focusing in 8 M urea revealed two differently charged subunits in each of the isolated lectins; a total of three different subunits in the three lectins was observed