Redgram (Cajanus cajan L.) extracts have been analyzed for the protease inhibitors using a new, sensitive, simple, and rapid method for detection of electrophoretically separated protease inhibitors. The detection involves equilibrating the gel successively in the protease assay buffer and protease solution, rinsing the gel in assay buffer, and later exposing it to an unprocessed x-ray film. Gelatin on the film in places corresponding to the inhibitor bands remains unhydrolyzed. A simple and inexpensive laboratory experiment to detect protease inhibitors of legume seeds by the gel-x-ray film contact print technique is described. (Contains 4 figures.)