The knowledge about biological activities of constituents from medicinal mushrooms belonging to the genus Tricholoma is limited. A 59-kDa laccase has now been purified from fresh fruiting bodies of the mushroom Tricholoma matsutake. The purification protocol entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, affinity chromatography on ConA-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. Of the various affinity and ion exchange chromatographic media employed, the laccase bound only on Con A-Sepharose. The activity of the laccase did not undergo major changes over the temperature range 20-80°C. However, all activity vanished following exposure to 100°C for 10 minutes. The enzyme activity varied only slightly over the pH range 3-5, with the optimal pH of 5, but exhibited a precipitous decline when the pH was increased to 6, and was undetectable at pH 8 and 9. The laccase showed activity in the decolorization of azo dyes without a mediator. Its N-terminal sequence demonstrated only slight resemblance to those of other mushroom laccases. The newly described laccase is distinctive from the previously isolated Tricholoma mushroom laccases in a number of aspects.