In a prospective study of consecutive patients with reflux esophagitis and/or hiatal hernia and Barrett's esophagus, the prevalence of Helicobacter pylori was assessed. Antral biopsy specimens were studied and a serum sample for detection of IgG antibodies against Helicobacter pylori was taken. As a reference group patients presenting with a normal esophagus, stomach, and duodenum were taken. Reflux esophagitis was diagnosed in 118 patients, hiatal hernia without esophageal inflammation in 109, and Barrett's esophagus in 13. Helicobacter pylori was present in 74 (30%) of these patients and in 204 (51%) of the reference group. Prevalence of Helicobacter pylori was significantly lower in all groups compared with the reference group (P < 0.001). There was no difference when patients with esophagitis, Barrett's esophagus, or hiatal hernia were compared. Patients with esophagitis and Helicobacter pylori in their antrum are significantly older than esophagitis patients without concomitant Helicobacter infection, 61.5 (SD, 17) versus 53 (SD, 17) years (P < 0.001). It is concluded that the prevalence of Helicobacter pylori infection in patients with gastroesophageal reflux disease is significantly lower than in the reference group, irrespective of the severity of esophagitis. Helicobacter pylori infection has no role in the pathogenesis of reflux esophagitis.