Twenty-one chronic hemodialysis patients were investigated. While only two had radiologic evidence of peptic ulceration, three had markedly elevated basal acid outputs, thirteen had significantly elevated maximal acid outputs and seven had fasting duodenogastric reflux. Elevated fasting serum gastrin levels and prolonged gastrin circulation following stimulated endogenous release were also demonstrated. The abnormalities in gastric function may be explained by fasting and stimulated hypergastrinemia.