Epidemiological studies demonstrate a negative association between Helicobacter pylori infection and gastro-oesophageal reflux disease and its complications. This might represent a protective effect because of the tendency for H. pylori infection to lower gastric acid secretion with advancing age. However, studies of the effect of H. pylori eradication on gastro-oesophageal reflux disease have failed to show any worsening of gastro-oesophageal reflux disease symptoms. Several interactions between H. pylori and proton-pump inhibitor therapy used to treat gastro-oesophageal reflux disease need to be considered. Helicobacter pylori infection improves the control of gastric acidity by proton-pump inhibitors and this produces a small advantage in clinical control of reflux disease. The infection prevents rebound acid hypersecretion occurring when proton-pump inhibitor therapy is discontinued. However, concerns have been expressed that the body gastritis induced by proton-pump inhibitor therapy in H. pylori-infected subjects might increase the risk of gastric cancer. At present, it is unclear whether H. pylori should be eradicated in gastro-oesophageal reflux disease patients.