Subcutaneous administration of bombesin (50-200 micrograms/kg), cholecystokinin-8 (10-100 micrograms/kg) and epidermal growth factor (10-100 micrograms/kg) but not calcitonin gene-related peptide (25 micrograms/kg), neurotensin (500 micrograms/kg) or substance P (200 micrograms/kg) produced a marked and dose-related inhibition of ethanol-induced gastric lesions in rats. 2. These actions were inhibited by a non-ulcerogenic dose of indomethacin suggesting that prostaglandins are involved in the protective activity of bombesin, cholecystokinin-8 and epidermal growth factor.