H. pylori is the major cause of gastritis in children and adults. Studies in children have demonstrated a specific association between H. pylori and primary gastritis. H. pylori colonization of the gastric mucosa is also important in relation to the natural history of duodenal ulcer disease. Duodenal ulcers do not appear to relapse if H. pylori is cleared from the gastric mucosa. Because of the low incidence of duodenal ulcer disease in children, a multicenter study is required to demonstrate whether this finding is true in children. To date, no specific symptoms have been associated with the presence of H. pylori gastritis in children. H. pylori gastritis may therefore be an asymptomatic condition in the majority of infected children. Further studies in relation to H. pylori gastritis and symptoms in children will be important because it should be easier to identify specific symptoms in children than in adults. H. pylori gastritis in children can be diagnosed by obtaining antral biopsy specimens for culture and histologic study during upper gastrointestinal endoscopy. Serologic study is also a sensitive and specific indicator of H. pylori infection, provided that children's sera are used to standardize the assay. Noninvasive tests such as 13C urea breath tests are very attractive for use in children but are expensive. H. pylori can be cleared from the gastric mucosa in as many as 70% of children by using a combination of metronidazole or amoxicillin with colloidal bismuth subcitrate or bismuth subsalicylate. Studies in children are important in determining the epidemiology of H. pylori. Children in Western societies are not usually colonized. Infection becomes more common with increasing age. Children in underdeveloped countries and those living in poor social conditions in Western countries are much more likely to be infected at a young age. The reason for the increased prevalence of infection among these groups is not known. There is also significant intrafamilial clustering of H. pylori infection. Again, it is unclear why the organism is clustered within households and institutions. Future studies on children will be of importance in determining whether H. pylori gastritis is a cause of specific symptoms, the epidemiology of H. pylori infection, and the possible role of the organism in the natural history of gastric cancer.