['The majority of reflux patients have non-erosive reflux disease.', 'To evaluate the influence of Helicobacter pylori on oesophageal acid exposure in patients with both non-erosive and erosive reflux disease and in a group of controls. The pattern and distribution of chronic gastritis were also assessed.', 'One hundred and twelve consecutive patients with symptoms of gastro-oesophageal reflux disease agreed to undergo both upper gastrointestinal endoscopy and 24-h oesophageal pH-metry. Patients were grouped as H. pylori-positive or H. pylori-negative on the basis of both CLO-test and histology, and as cases with or without oesophagitis on the basis of endoscopy. The controls consisted of 19 subjects without reflux symptoms and with normal endoscopy and oesophageal pH-metry.', 'H. pylori was positive in 35 patients (31%) and in six controls (31%); oesophagitis was found in 44 patients (39%) and non-erosive reflux disease in 68 (61%). The prevalence of chronic gastritis in the antrum and corpus was higher in H. pylori-positive than in H. pylori-negative patients (P < 0.001), but was more frequently mild (P < 0.001) than moderate or severe. The percentage total time the oesophageal pH < 4.0 was higher in patients than in controls (P < 0.008-0.001), but there was no difference between H. pylori-positive and H. pylori-negative patients (12.3% vs. 12%, P = 0.43) or H. pylori-positive and H. pylori-negative controls (1.07% vs. 1.47%, P = 0.19).'] Is helicobacter pylori infection involved in the pathogenesis of either erosive or non-erosive gastro-oesophageal reflux disease?