An isolate of Penicillium purpurogenum produces lytic enzymes which are directly implicated in the degradation of fungal cell walls and are associated with its own growth and autolysis. Maximal β-1,3-glucanase activity was detected after 45 d of growth (2347 mU mg−1 protein) in a stationary culture, and after 12 d of incubation (1533 mU mg−1 protein) in a shake culture. Other enzymatic activities detected in stationary liquid cultures were β-1,3,(4)-glucanase (with two maxima of approx 100–120 mU mg−1 protein at 14 and 50 d of growth), β-1,6-glucanase (317 and 270 mU mg−1 protein at days 3 and 13, respectively) and polymethyl-galacturonase (914 and 951 mU mg−1 protein at days 5 and 12, respectively). The chitinase activity was low. P. purpurogenum directly attacked the mycelium of Monilinia laxa when the two fungi were grown together. The enzymatic complex of P. purpurogenum also attacked the mycelium of M. laxa lysing its hyphae and spores, resulting in complete destruction of the mycelia. © 1993, British Mycological Society. All rights reserved.