Solid-state and liquid-state fermentations were carried out to evaluate the effect ofRhizopus oligosporuson the trypsin inhibitor of denatured black gram grits. The trypsin inhibitor fraction was released into the supernatant, attaining a maximum concentration by 72 h of incubation, as indicated by its activity. The increase in trypsin inhibitor activity was approximately threefold in solid-state fermentation and approximately fivefold in liquid-state fermentation. Results indicated that the spore-free culture filtrate prepared fromR.oligosporuscontained "releasing factor(s)" which were effective on black gram grits. The effect of the spore-free culture filtrate on black gram trypsin inhibitor suggests the presence of a factor in the culture filtrate which inactivates the trypsin inhibitor fraction.