SummarySeven lower phycomycetes,Afhanomyees astaci, A. euteiches, A. cladogamus, A. cochlioides, A. laevis. Pythiumsp andSaprolegnia sp., have been investigated in respect of chitinolytic and cellulolytic activity. The five Aphanomyces species were also tested for pectinolytic activity. Different ages of stationary and shaken cultures, 2 or 3 different substrates, and 2 test pH were used for each enzyme to be tested. Chitinase and cellulase were assayed with 2 different methods.All the fungi showed chitinase activity, although in varying degree. In liquid cultures the strains ofA. astacigave the by far highest ac tivity. Differenl results were obtained with different growth media aud lest methods.Chitinase of some of the fungi was readily adsorbed on chilin. Adsorbed chitinase seemed to withstand heating more than unadsorbed enzyme.Only the three plant parasites,A. euteiches, A. cladogamusandA. codilioides, showed appreciable cellulase and pectinase activities which in some cases were stimulated by the presence in the medium of the enzyme substrate.Different assay methods and growth conditions showed difterent pattern regarding the difference in activity between the tested fungi and between used media.The conceivable roles in vivo of found activities were discussed.