The effects of the carbon and nitrogen sources, initial pH and incubation temperature on laccase production by Trametes modesta were evaluated using the one-factor-at-a-time method. The final optimisation was done using a central composite design resulting in a four-fold increase of the laccase activity to 178 nkat ml(-1). Response-surface analysis showed that 7.34 g l(-1) wheat bran, 0.87 g l(-1) glucose, 2.9 g l(-1) yeast extract, 0.25 g l(-1) ammonium chloride. an initial pH of 6.95 and an incubation temperature of 30.26 degreesC were the optimal conditions for laccase production. Laccase produced by T. modesta was fully active at pH 4 and at 50 degreesC. The laccase was very stable at pH 4.5 and at 40 degreesC but half-lives decreased to 120 and 125 min at higher temperature (60 degreesC) and lower pH (pH 3).