AbstractWe have studied changes in the activity of some lytic enzymes contained in mycelium ofAspergillus nigerin cultures relative to the autolytic phase of growth. Acid phosphatase, polygalacturonidase and α‐amylase activity reached its highest level (40.7, and 8 U/sample, respectively) at the initiation of the autolytic phase of growth. 1,3‐ß‐Glucanase and ß‐N‐acetylglucosaminidase reached its highest level (3.5 and 2 U/sample, respectively) during the first days of autolysis.Alkaline phosphatase, cellulase, invertase, esterase, chitinase and proteolytic activity is also present in autolysing mycelium ofA. niger, though comparatively low. Their maximum activity coincided with the beginning of the autolytic phase of growth. In all enzymes studied here, as autolysis proceeded, enzyme activity decreased by about 90%. Only esterase activity remained nearly constant throughout the whole period of autolysis de