Thelephora terrestris, an ectomycorrhizal hymenomycete, produces extracellular laccase when grown in minimal liquid medium. The enzyme was characterized as a protein of 66 kDa. The optimal pH varied depending on the substrate utilized, being 5.0 for syringaldazine, 4.8 for guaiacol and 3.4 for ABTS. The Km was 2.52±0.4 μM for syringaldazine, 16±1.9 μM for ABTS and 120.6±4.9 μM for guaiacol. The secretion of laccase was biomass-dependent and independent of the glucose concentration in the medium. The addition of inducers did not increase laccase production which was dependent upon the ammonium phosphate concentration.