This study was designed to evaluate the efficacy of an orally administered aqueous extractof glutinous rice (GRE) to protect against acute gastric mucosal lesions inducedby ethanol, indomethacin, and water immersion restraint stress in rats and to characterizethe active substances responsible for the protection. GRE was shown to dose-dependentlyprevent the gastric lesions induced by the above ulcerogenic treatments atdoses of 30 to 300 mg/kg. GRE treatment increased the gastric mucin content and partiallyblocked the ethanol-induced depletion of the gastric mucus layer. Also, it increasedthe nonprotein sulfhydryl concentration in the gastric mucosa. The gastroprotectiveaction of GRE was markedly enhanced by co-treatment with 4-8 mg/kg tea extracts. The activity of GRE was completely lost by heat treatment at 80oC for 3 min or treatmentwith 0.01% pepsin at 37oC for 1 h. Protein extraction studies indicated that prolaminsare involved in the gastroprotective activity of GRE. Our results suggest that glutinousrice proteins are useful for the prevention and treatment of gastritis and peptic ulcer.