Gastro-oesophageal reflux disease may develop following eradication of Helicobacter pylori. However gastro-oesophageal reflux disease could be preexistent and misdiagnosed since patients often misinterpret gastro-oesophageal reflux disease symptoms or focus their attention on abdominal symptoms. A questionnaire for analysis of gastro-oesophageal reflux disease symptoms has not been used until now. A total of 70 patients with duodenal ulcer and Helicobacter pylori gastritis, without oesophagitis and/or typical gastro-oesophageal reflux disease symptoms were studied. All patients received a questionnaire with 5 items focused on abdominal symptoms and 5 on gastro-oesophageal reflux disease symptoms. The two symptom scores were calculated separately. After Helicobacter pylori treatment, follow-up consisted of clinical controls every 3 months for 1 year. Patients were asked to describe their complaints and to answer the questionnaire. If gastro-oesophageal reflux disease symptoms recurred endoscopy was performed. At interview, all patients reported a significant improvement in their abdominal symptoms after eradication; however 23 patients (32.8%: group A) reported the occurrence of gastro-oesophageal reflux disease symptoms, and 5 of them developed oesophagitis; gastrooesophageal reflux disease symptoms did not appear in the remaining 47 patients (group B). Basal gastro-oesophageal reflux disease score was significantly higher in group A than in group B (1.9+/-1.5 vs 0.9+/-0.9, p<0.005), while the abdominal symptoms score was not different. Following eradication, the score for abdominal symptoms decreased significantly (4.2+/-1.5 vs 1+/-0.8, p<0.0001) in the two groups; conversely, the total gastro-oesophageal reflux disease score remained unchanged, improving in 2 patients in group A and 11 in B, and worsening in 5 in group A and in 1 in B. Presence of hiatus hernia and male sex significantly correlated with the development of reflux symptoms. Patients who present with gastro-oesophageal reflux disease after Helicobacter pylori eradication are likely to already be affected by gastro-oesophageal reflux disease.