Epidermal growth factor (EGF) has been shown to enhance healing of experimental gastric ulcers when given subcutaneously or orally in the drinking water. This effect of EGF occurs without reducing gastric acid secretion. On the other hand, EGF reportedly is excreted rapidly from gastric lumen when administered by intragastric bolus. This suggests that further stimulation of ulcer healing may be expected if EGF is given with an acid-suppressive agent or with an agent allowing EGF to remain in rat gastric lumen at high concentrations. In the present study, EGF administered by gastric intubation at a dose of 10 micrograms/kg, which is three times smaller than reported in previous studies, was evaluated for its effect on acetic acid-induced rat gastric ulcers in combination with sucralfate or omeprazole. Sucralfate is well known selectively to bind proteins covering the ulcer base, and omeprazole is a potent acid-suppressive agent. Prior to the study of combined EGF and sucralfate, oral sucralfate was confirmed to allow endogenous gastric EGF and mouse EGF given exogenously to remain at high concentrations in gastric contents and tissues. EGF and sucralfate (2 g/kg/day) given alone failed to stimulate ulcer healing in submandibularectomized rats (SMR rat) whose endogenous gastric EGF was depleted. However, the combination of both drugs administered at the same doses significantly accelerated ulcer healing in the SMR rat. Omeprazole (200 mg/kg/day) significantly enhanced ulcer healing regardless of removal of the submandibular glands. The combination of EGF and omeprazole further stimulated ulcer healing in the SMR rat.(ABSTRACT TRUNCATED AT 250 WORDS)