AIM: To compare Helicobacter pylori infection and gastric mucosal histological features of gastric ulcer patients with chronic gastritis patients in different age groups and from different biopsy sites. METHODS: The biopsy specimens were taken from the antrum, corpus and upper angulus of gastric ulcer and chronic gastritis patients. Giemsa staining, improved Toluidine-blue staining and H pylori-specific antibody immune staining were performed as appropriate for the histological diagnosis of H pylori infection. Hematoxylineosin staining was used for the histological diagnosis of activity of H pylori infection, mucosal inflammation, glandular atrophy and intestinal metaplasia and scored into four grades according to the Updated Sydney System. RESULTS: Total rate of H pylori infection, mucosal inflammation, activity of H pylori infection, glandular atrophy and intestinal metaplasia in 3 839 gastric ulcer patients (78.5%, 97.4%, 82.1%, 61.1% and 64.2%, respectively) were significantly higher than those in 4 102 chronic gastritis patients (55.0%, 90.3%, 56.2%, 36.8%, and 37.0%, respectively, P<0.05). The rate of H pylori colonization of chronic gastritis in <30 years, 31-40 years, 41-50 years, 51-60 years, 61-70 years and >70 years age groups in antrum was 33.3%, 41.7%, 53.6%, 57.3%, 50.7%, 43.5%, respectively; in corpus, it was 32.6%, 41.9%, 53.8%, 60.2%, 58.0%, 54.8%, respectively; in angulus, it was 32.4%, 42.1%, 51.6%, 54.5%, 49.7%, 43.5%, respectively. The rate of H pylori colonization of gastric ulcer in <30 years, 31-40 years, 41-50 years, 51-60 years, 61-70 years and >70 years age groups in antrum was 60.5%, 79.9%, 80.9%, 66.8%, 59.6%, 45.6%, respectively; in corpus, it was 59.7%, 79.6%, 83.6%, 80.1%, 70.6%, 59.1%, respectively; in angulus, it was 61.3%, 77.8%, 75.3%, 68.8%, 59.7%, 45.8%, respectively. The rate of H pylori colonization at antrum was similar to corpus and angulus in patients, below 50 years, with chronic gastritis and in patients, below 40 years, with gastric ulcer. In the other age- groups, the rate of H pylori colonization was highest in corpus, lower in antrum and lowest in angulus (all P<0.05). The rates of glandular atrophy and intestinal metaplasia were higher and earlier in H pylori-positive patients than those without H pylori infection (both P<0.01). In comparison of gastric ulcer patients with chronic gastritis patients, the rate of glandular atrophy and intestinal metaplasia was higher in H pylori-positive patients with gastric ulcer than in H pylori-positive patients with chronic gastritis (both P<0.01); the rate of glandular atrophy and intestinal metaplasia were also higher in H pylori-negative patients with gastric ulcer than in H pylori-negative patients with chronic gastritis (both P<0.01). Both glandular atrophy and intestinal metaplasia were much more commonly identified in the angulus than in the antrum, lowest in corpus (all P<0.01). CONCLUSION: Rate of H pylori infection, glandular atrophy and intestinal metaplasia in gastric ulcer were higher than in chronic gastritis in all-different age -groups. Distribution of H pylori colonization is pangastric in the younger patients. It is highest in corpus, lower in antrum and lowest in angulus in the older age groups. Progression of glandular atrophy and intestinal metaplasia seem to have a key role in the distribution of H pylori colonization. H pylori appears to be the most important risk factor for the development of glandular atrophy and intestinal metaplasia, but it is not the only risk. AIM: To compare Helicobacter pylori infection and gastric mucosal histological features of gastric ulcer patients with different gas groups in different age groups and from different biopsy sites. METHODS: The biopsy specimens were taken from the antrum, corpus and upper angulus of gastric ulcer and chronic Gastritis patients. Giemsa staining, improved Toluidine-blue staining and H pylori-specific antibody immune staining were performed as appropriate for the histological diagnosis of H pylori infection. Hematoxylineosin staining was used for the histological diagnosis of activity of H pylori infection, mucosal inflammation, Glandular atrophy and intestinal metaplasia and scored into four grades according to the Updated Sydney System. RESULTS: Total rate of H pylori infection, mucosal inflammation, activity of H pylori infection, glandular atrophy and intestinal metaplasia in 3 839 gastric ulcer patients (78.5% 97.4%, 82.1%, 61.1% and 64.2%, respectively) respectively were significantly high er than those in 4 102 chronic gastritis patients (55.0%, 90.3%, 56.2%, 36.8% and 37.0% respectively, respectively, P <0.05). The rate of H pylori colonization of chronic gastritis in <30 years, 31-40 Years, 41-50 years, 51-60 years, 61-70 years and> 70 years Age groups in antrum was 33.3%, 41.7%, 53.6%, 57.3%, 50.7%, 43.5%, respectively; in corpus, it was The rate of H pylori (32.6%, 41.9%, 53.8%, 60.2%, 58.0%, 54.8% respectively) was 32.4%, 42.1%, 51.6%, 54.5%, 49.7%, 43.5% respectively Colonization of gastric ulcer in <30 years, 31-40 years, 41-50 years, 51-60 years, 61-70 years and> 70 years age groups in antrum was 60.5%, 79.9%, 80.9%, 66.8%, 59.6 It was 59.7%, 79.6%, 83.6%, 80.1%, 70.6%, 59.1%, respectively; in angulus, it was 61.3%, 77.8%, 75.3%, 68.8%, 59.7% %, 45.8%, respectively. The rate of H pylori colonization at antrum was similar to corpus and angulus in patients, below 50 years, with chronic gastritis and in patients, below 40 years,with gastric ulcer. In the other age groups, the rate of H pylori colonization was highest in corpus, lower in antrum and lowest in angulus (all P <0.05). The rates of glandular atrophy and intestinal metaplasia were higher and earlier in H In gastric ulcer patients with chronic gastritis, the rate of glandular atrophy and intestinal metaplasia was higher in H pylori-positive patients with gastric ulcer than in H the rate of glandular atrophy and intestinal metaplasia were also higher in H pylori-negative patients with gastric ulcer than in H pylori-negative patients with chronic gastritis (both P <0.01) Both glandular atrophy and intestinal metaplasia were much more commonly identified in the angulus than in the antrum, lowest in corpus (all P <0.01). CONCLUSION: Rate of H pylori infection, glandular atrophy and intestinal m etaplasia in gastric ulcer were higher than in chronic gastritis in all-different age-groups. Distribution of H pylori colonization is pangastric in the younger patients. It is highest in corpus, lower in antrum and lowest in angulus in the older age groups. Progression of glandular atrophy and intestinal metaplasia seem to have a key role in the distribution of H pylori colonization. H pylori appears to be the most important risk factor for the development of glandular atrophy and intestinal metaplasia, but it is not the only risk.