Elastolytic and elastase inhibitory activities were investigated for 13 strains of Aspergillus fumigatus, three strains of Aspergillus flavus and three strains of Aspergillus niger. Nine of the 13 strains of A. fumigatus and all strains of A. flavus demonstrated elastase activity (more than 1 unit ml(-1)). Six of the 13 strains of A. fumigatus and all strains of A. flavus expressed elastase inhibitory activity (more than 2 units ml(-1)). However, no elastase or elastase inhibitory activities were observed with A. niger. It was also found that crude elastase inhibitors from six strains of A. fumigatus and two strains of A. flavus were stable to heat treatment at 100 degrees C for 10 min. In addition, human leukocyte elastases were inhibited by crude elastase inhibitors from A. fumigatus and A. flavus; however, no effect was observed on the elastase derived from porcine pancreas.