Uric acid was evaluated for its potential to protect the gastric mucosa against the injuries caused by 80% ethanol, 0.6 m-HCl and 0.2 M-NaOH in rats. Uric acid at doses of 50, 100 or 300 mg/kg body weight provided dose-dependent protection against the ulcerogenic effects of all three agents. Other effects caused by ethanol only were studied. Serum uric acid concentrations were statistically significantly increased by both uric acid and ethanol treatments. Treatments of rats by gavage with 1 ml 80% ethanol was found to cause depletion of stomach-wall mucus, to lower the concentrations of protein, nucleic acids and non-protein sulphydryl groups in the stomach wall, and to cause histopathological lesions, including necrosis, erosions, congestion and haemorrhage, of the stomach wall. Treatment with uric acid, at doses of 50, 100 or 300 mg/kg body weight, by gavage, provided some measure of protection against all of these effects, and the protection was generally dose dependent. The protective effects of uric acid against damage to the gastric-wall mucosa may be mediated through its effects on mucus production and non-protein sulphydryl concentrations, and/or its free-radical scavenging properties.