Pigeon-pea seed extracts have been analyzed for the protease inhibitors using a new, sensitive and simple method for visualization of electrophoretically separated protease inhibitors. The visualization involves equilibrating the gel successively in the protease assay buffer, protease solution, rinsing the gel in protease assay buffer, and exposing it to an exposed, undeveloped X-ray film. Gelatin on the film in places corresponding to the inhibitor bands remains unhydrolyzed. By this method the pigeon-pea seed extract was found to contain nine trypsin and at least seven chymotrypsin inhibitors but no papain or bromelain inhibitors.