A laccase from Pycnoporus sanguineus was purified by two steps using phenyl-Sepharose columm. A typical procedure provided 54.1-fold purification, with a yield of 8.37%, using syringaldazine as substrate. The molecular weight of the purified laccase was 69 and 68 kDa as estimated by 12% (w/v) SDS-PAGE gel and by gel filtration, respectively. The K-m values for the substrates ABTS, syringaldazine, and guaiacol were 58, 8.3, and 370 mu M, respectively. The enzyme's pH optimum for syringaldazine was 4.2 and optimal activity was 50 degrees C. The enzyme showed to be thermostable because when kept at 50 degrees C for 24 and 48 h it retained 93 and 76% activity. This laccase was inhibited by L-cysteine, P-mercaptoethanol, NaN3, NaF, and HgCl2.