Bovine dorsal root, the dorsal half of bovine spinal cord or guinea-pig''s whole brain was extracted with 70% ethanol at room temperature. When the extract was incubated with trypsin after being concentrated in vacuo, substance P (SP), present in the original extract, was destroyed but gut-stimulating activity remained. This could be ascribed to a new component (CT). CT was extracted by a procedure similar to Rocha and Silva''s extraction method of crude bradykinin and seemed to be of polypeptide nature. The stimulating activity of CT on guinea-pig ileum was barely affected by atropine, tryptamine, cocaine, tetramethylammonium, hexamethonium, morphine, GABA and [epsilon] -amino-N-caproic acid and so resembles that of SP. But contraction produced by CT is slower, not abolished by previous administration of SP, nor potentiated by LSD, but depressed by a high dose of pyribenzamine. Using guinea-pig''s ileum, hen''s rectal cecum, and rat''s uterus and colon, it was proved that CT action is rather similar to that of plasma kinin and different from that of substance P. The higher the SP content of the tissue, the more CT was obtained on incubation with trypsin. Dorsal spinal cord and small intestine yielded higher CT activity than skeletal muscle and ventral cord.