The effects of human epidermal growth factor(EGF) which was produced by recombinant DNA technique was investigated on gastric secretion, gastric lesion and ulcer models in rats. The EGF showed significant inhibition of secretion of gastric juice and total acid output, at 0.4mg/kg, id and also inhibited Shay ulceration at 0.4mg/kg, id in rats. The lesion induced by absolute ethanol was significantly reduced by oral administration of EGF at 0.4mg/kg. Likewise, EGF caused significant inhibition of indomethacin induced gastric ulcer at oral doses of 0.2 and 0.4mg/kg. The EGF produced dose-dependent inhibition of gastric ulcer induced by acidified aspirin, but showed no significant inhibition at oral doses of 0.1, 0.2 and 0.4mg/kg. The chronic gastric ulcer induced by injection of 20% acetic acid solution was significantly reduced by oral doses of 0.1 and 0.4mg/kg of EGF. Duodenal ulcer induced by mepirizole was dose-dependently inhibited by oral doses of 0.1, 0.2 and 0.4mg/kg of EGF. These data suggest that EGF possesses pronounced inhibitory action in gastric ulcer and duodenal ulcer of rats.