Spinal cord of the rat was transected at C7 level to produce acute gastric ulcer. It was observed as follows: (1) The body temperature (B.T.) of the cord transected animals fell in a good agreement with ambient temperature. It appears that the fall in B.T. is one of the main causes inducing ulceration. (2) Administration of epinephrine decreased ulceration and prevented the fall in B.T. both in a dose-dependent manner. (3) Cord transection induced ulcer formation was markedly attenuated by adrenalectomy and exacerbated again by displacement with dexamethasone, but the fall in B.T. was unaffected at all in either case. (4) The variations in acid secretory and endocrine function of gastric mucosa after transection might be involved in ulcer formation.