Helicobacter pylori is probably the most important factor in the pathogenesis of peptic ulcer disease in the absence of other precipitating factors, such as the intake of ulcerogenic drugs. Clinical studies have shown convincingly that eradication of H. pylori dramatically alters the long-term natural history of this chronic relapsing disorder, and that ulcer recurrences following eradication are rare. Available evidence also suggests that figures for H. pylori reinfection are low in adults in developed countries following eradication. In addition, H. pylori eradication may prevent peptic ulcer bleeding or rebleeding. Curing H. pylori infection significantly increases the quality of life of patients with duodenal ulcer disease and is, to date, the most cost-effective treatment in the long-term management of this disease. Ulcer patients presenting with recurrent dyspeptic symptoms after apparently successful eradication of H. pylori should be checked for ulcer and H. pylori recurrence, as well as for reflux oesophagitis, which has been shown to occur in about 9% of patients with duodenal ulcer disease and previously cured of H. pylori infection. We would also argue that H. pylori infection in young patients with dyspepsia should be treated, although this issue will remain controversial until well-designed, placebo-controlled studies establish the real benefits of eradication therapy in the long-term treatment of this disease.