Laccases are very interesting biocatalysts for several industrial applications. Its production by different white-rot fungi can be stimulated by a variety of inducing substrates, and the use of lignocellulosic wastes or industrial by-products is one of the possible approaches to reduce production costs. In this work, various industrial wastes were tested for laccase production by Trametes versicolor MZKI G-99. Solid waste from chemomechanical treatment facility of a paper manufacturing plant showed the highest potential for laccase production. Enzyme production during submerged cultivation of T. versicolor on the chosen industrial waste has been further improved by medium optimization using genetic algorithm. Concentrations of five components in the medium were optimized within 60 shake-flasks experiments, where the highest laccase activity of 2,378 U dm(-3) was achieved. Waste from the paper industry containing microparticles of CaCO(3) was found to stimulate the formation of freely dispersed mycelium and laccase production during submerged cultivation of T. versicolor. It was proven to be a safe and inexpensive substrate for commercial production of laccase and might be more widely applicable for metabolite production by filamentous fungi.