Effects of a new minor tranquilizer, CS-386 and diazepam were studied upon the gastric contraction and excitation of lumbar gamma-motoneurons following stimulation of some of the brain structures as well as upon the spontaneous gastric motility in the cat. CS-386 inhibited the hypothalamus-induced gastric contraction with little changes in spontaneous motility at doses of 5 and 10 mg/kg (i.d.). Diazepam inhibited both the hypothalamus-induced contraction and spontaneous motility at these doses. The vagal nerve-induced gastric contraction was suppressed by diazepam (5 mg/kg, i.d.) but not by the same dose of CS-386. Bemegride (5 mg/kg, i.v.) antagonized almost completely the depression caused by 5 mg/kg of CS-386, but not that by a dose of 10 mg/kg or 5 as well as 10 mg/kg of diazepam. Excitation of the lumbar gamma-motoneuron following stimulation of the posterior hypothalamus or the mesencephalic reticular formation was depressed by CS-386 or diazepam (10 mg/kg, p.o.), but not by lower doses. Based on the these evidences, it was suggested that CS-386 could be effective in stress-induced gastric lesions with lower side effects in digestive organs than diazepam.