Unique features of Helicobacter pylori disease in children. In a six-year period, 41 children had endoscopically documented duodenal ulcer disease or primary H. pylori antral gastritis without duodenal ulcer. Of 37 children with H. pylori gastritis, group 1 comprised 23 patients with duodenal ulcer disease and group 2 had 14 patients without ulcers (primary H. pylori gastritis). Group 3 comprised four children with duodenal ulcer disease and H. pylori-negative antral biopsies. During the study period, all primary chronic ulcer disease was duodenal; no primary chronic gastric ulcer was present. Two distinct types of duodenal ulcer disease were identified; the majority (85%) was always associated with significant active H. pylori antral gastritis (group 1). The minority (15%) had virtually absent gastritis and no H. pylori (group 3). Native Indian children were represented in group 1 quite out of proportion to the referral population and had the most severe disease. While it is established that a higher prevalence of asymptomatic H. pylori infection exists in non-Caucasians, this appears to be the first demonstration of a higher prevalence of symptomatic ulcer disease in non-Caucasian children or adults. Caucasian children tended to have primary H. pylori gastritis (group 2) or duodenal ulcer without H. pylori (group 3). Antral nodularity was found to be an important specific endoscopic sign, unique to those children with H. pylori disease. It has not been described in adult H. pylori disease. Non-Caucasian children, especially Native Indians, in British Columbia have more prevalent and more severe H. pylori disease than Caucasians. Endoscopy with gastric antral biopsies is necessary to distinguish different types of duodenal ulcer disease and to diagnose primary H. pylori gastritis. 