- The relationship between Helicobacter pylori infection and chronic dyspepsia is controversial. To determine the effect of H. pylori infection on dyspeptic symptoms, we compared the prevalence of H. pylori infection in immigrants from developing countries and people born in industrialized countries. Upper abdominal symptoms were assessed by a questionnaire and H. pylori infection was determined with a 13C-urea breath test and serology. H. pylori infection was found in 63% of subjects from developing countries and 11% of subjects from industrialized countries. There was no difference in the prevalence of dyspeptic symptoms between the 2 groups. The lack of difference in chronic dyspeptic symptoms between the groups, despite a major difference in the H. pylori prevalence, suggests that H. pylori infection is not a major contributor to chronic dyspepsia.