The lipolytic activity in supernatant fractions of cultures of Saccharomycopsis lipolytica, Micrococcus caseolyticus, Bacillus licheniformis and a Staphylococcus sp. was studied. Nutrient broth with and without emulsified olive oil was used as substrate. Optimal pH values and temperatures for the lipase produced by the 4 different microorganisms were determined. The lipolytic activity generally reached a maximum after incubation for 2 to 6 days. The subsequent decrease in the lipolytic activity was associated with a high proteolytic activity only for Micrococcus caseolyticus. The lipolytic activity was decreased by the presence of olive oil in the medium. Determination of the lipolytic activity after a certain time of incubation, the maximal lipolytic activity and a time integrated lipolytic activity are compared as estimators for the potential hydrolytic capacity of micro organisms.