The effects of gefarnate on several acute gastric lesions were studied in rats. Gefarnate, given at either 100 approximately 1000 mg/kg orally or intraduodenally, dose-dependently inhibited the formation of gastric lesions induced by HCl-ethanol, HCl-taurocholate and aspirin. Cimetidine, given at 30 approximately 100 mg/kg as a reference drug, also significantly inhibited both HCl-ethanol and aspirin-induced lesions. The present study suggests that gefarnate, as well as cimetidine, is useful for the treatment of acute gastric lesions in man.