The secretion of enzymes involved in biocontrol from the wild T. harzianum strains Th11 and Th12 and the mutants Th11A80.1, Th11C40.1 and Th12A10.1 was studied after their cultivation in the presence of R. solani cell walls as the sole carbon source. The results showed that endoprotease activity in the supernatants from Th11A80.1 and Th11C40.1 increased 2.77 and 4.79-fold, respectively, and the beta-1,3-glucanase and beta-1,4-chitinase activity from Th12A10.1 increased 1.86 and 1.54-fold, respectively, compared with the corresponding parental strains. The role of the three enzymes in the biocontrol of R. solani is discussed.