B. cinerea produces extracellular acid proteinases: aspartic proteinase and carboxypeptidase, separable on CM-Sepharose CL-6B. Aspartic proteinase showed the maximum activity at pH 2.5-3.0, was inactivated by diazoacetyl-DL-norleucine methyl ester and was unable to hydrolyse carbobenzoxy Glu-Tyr. Carboxypeptidase showed the maximum activity at pH 4.7-5.0, was inactivated by diisopropyl fluorophosphate, and carbobenzoxy-Glu-Tyr served as an efficient enzyme substrate. The isolated aspartic proteinase hydrolysed proteins in the preparations of apple cell walls. Excretion of aspartic proteinase by B. cinerea preceded that of carboxypeptidase.