Abstract: The anti-ulcer effect of betaine was evaluated in rat model of HCl-ethanol induced gastric ulcer. Oral administration of HCl-ethanol caused a significant increase in the number of lesions in the gastric mucosa, volume of gastric juice, acidity and decreased activity of the pepsin. An increased level of lipid peroxidation and diminished tissue antioxidant system was also observed. Pre oral treatment with betaine (250 mg/kg/day for 21 days) counteracted all these changes induced by HCl-ethanol and maintained the rats at near normalcy. The gastro protective potential was further confirmed by histopathological studies of the gastric mucosa. The anti-ulcerogenic activity of betaine might be ascribable to its ability to neutralize the hydrochloride secreted into the stomach and/or to its free radical scavenging activity which protects the gastric mucosa against oxidative damage by decreasing lipid peroxidation and strengthening the mucosal barrier.