To define the clinical and pathological characteristics of Helicobacter pylori-associated gastritis, 173 patients with chronic gastritis, including 99 Hp-positive and 74 Hp-negative patients were studied. We found that there were no significant differences between Hp-positive and Hp-negative patients with regard to clinical symptoms, gastric acid secretion and serum basal gastrin level, whereas the grades of chronic gastritis and active gastritis were markedly higher in Hp-positive patients. 91.2% of patients with active gastritis had evidence of Hp infection. With the increase in Hp density, the proportion of high grades (II and III) gastritis tended to increase, especially the severe active gastritis. In addition, glandular atrophy and intestinal metaplasia in antral mucosa were significantly commoner in Hp-positive patients. There were no significant differences between the two groups in duodenogastric reflux rate, but the reflux rate over moderate degree in Hp-positive patients (19.59%) was somewhat lower that in Hp-negative patients (36.36%) (P = 0.09).