Seed extracts from indigenous and introduced legumes were prepared and used to search for inhibitors of fish muscle proteinases. Fish flesh extracts were prepared from samples of Merluccius productus (Pacific whiting or merluza) obtained off the Oregon coast and in the Gulf of California, respectively. The proteinase activity in the fish muscle for the Pacific whiting was the highest, followed by parasitized merluza. The lowest proteinase activity was for the nonparasitized merluza. Six out of 12 seed extracts reduced the proteinase activity from the fish flesh by more than 50%. The reduction of enzyme activity was higher for samples of fish flesh extracts from the Gulf of California than for the Oregon samples. Seed extracts also reduced the proteinase activity of commercial serine and cysteine proteinases such as trypsin, chymotrypsin, and papain. This inhibitory capacity was maintained even after heating the seed extracts to 90 degrees C for 15 min. Several seed extracts show promise for use as proteinase inhibitors during production of surimi, the intended commercial product of massive fisheries such as Pacific whiting or merluza