An N-acetylglucosamine-binding lectin with a molecular mass of 32kDa was isolated from fresh sclerotia of the edible mushroom Pleurotus tuber-regium. Its N-terminal sequence exhibited some similarity to that of Agaricus bisporus lectin. The isolation procedure was simple, involving (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on N-acetyl-D-glucosamine-agarose, and gel filtration by fast protein liquid chromatography on Superdex 75. The lectin exhibited hemagglutinating activity toward trypsinized rabbit erythrocytes but not toward untrypsinized rabbit erythrocytes.