The aim of the present study was to evaluate rebamipide in the prevention of indomethacin-induced gastric mucosal injury in healthy volunteers. Twenty healthy males (mean age 21.8 years, range 20-26) participated. This is a randomized, double-blind, placebo-controlled study. The 20 subjects were randomized to either indomethacin 25 mg three times a day and placebo three times a day or indomethacin and rebamipide 100 mg three times a day for seven days. Endoscopy was performed at baseline and again after the treatment. In the placebo group, eight of 10 subjects (80%) developed symptoms compared to three of seven (43%) in the rebamipide group. The incidence of gastric lesions was 70% in the placebo group, which was significantly higher than that in the rebamipide group (14%). The lipid peroxide levels in the mucosa of the gastric body significantly increased in the placebo group. This increase was not inhibited by rebamipide. Myeloperoxidase activity in the gastric mucosa tended to increase in the placebo group, but tended to decrease in the rebamipide group. These results indicate that rebamipide may be an effective prophylaxis against indomethacin-induced gastropathy in humans.