Biological pretreatments with three selected strains of Panus tigrinus were used for delignification of sugarcane bagasse. The fungi with potential for delignification were analyzed by determining the chemical composition of the decayed bagasse samples, and the selectivity in terms of weight loss of the different components was evaluated. All the strains grow abundantly on bagasse as unique carbon source. After determining the chemical composition of degraded bagasse, P. tigrinus FTPT-4745 was selected as the most efficient strain on a 6-g scale, since the carbohydrates were preserved. P. tigrinus FTPT-4741 and FTPT-4742 were the most efficient strains on a large scale (100 g).