The effect of centrally administered losartan, an angiotensin-2 receptor antagonist on gastric acid secretion and gastric cytoprotection was studied using different models of gastric ulcers such as acetic acid-induced chronic gastric ulcers, pylorus ligation, ethanol induced and stress induce acute gastric ulcer and cysteamine hydrochloride induced duodenal ulcer. Losartan was administered intracerebroventrically at two different doses of 125 micro gm/kg and 250 micro gm/kg. Both doses of losartan increased healing of ulcer in acetic acid induced chronic gastric ulcer model. In pylorus legated rats, a significant reduction in free acidity, total acidity and ulcer index was observed with high dose while low dose produced reduction in free acidity and ulcer index. Both doses also showed significant antiulcer effect in ethanol-induced and stress-induced gastric ulcers. Losartan also reduced ulcer area in cysteamine-induced duodenal ulcer. It was concluded that angiotensin II receptor antagonism in brain increases healing of gastric ulcers and also prevents development of gastric and duodenal ulcers in rats.