BACKGROUND: Helicobacter pylori (H pylori) is the main cause of peptic ulcer disease. The role of H pylori in non-ulcer dyspepsia is less clear. OBJECTIVES: To determine the effect of H pylori eradication on dyspepsia symptoms in patients with non-ulcer dyspepsia. SEARCH STRATEGY: Trials were identified through electronic searches of the Cochrane Controlled Trials Register (CCTR), MEDLINE, EMBASE, CINAHL and SIGLE, using appropriate subject headings and keywords, searching bibliographies of retrieved articles, and through contacts with experts in the fields of dyspepsia and with pharmaceutical companies. These searches were updated in October 2004. SELECTION CRITERIA: All parallel group randomised controlled trials (RCTs) comparing drugs to eradicate H pylori with placebo or other drugs known not to eradicate H pylori for patients with non-ulcer dyspepsia. DATA COLLECTION AND ANALYSIS: Data were collected on individual and global dyspeptic symptom scores, quality of life measures and adverse effects. Dyspepsia outcomes were dichotomised into minimal/resolved versus same/worse symptoms. MAIN RESULTS: Seventeen randomised controlled trials were included in the systematic review. Fourteen trials compared antisecretory dual or triple therapy with placebo antibiotics +/- antisecretory therapy, and evaluated dyspepsia at 3-12 months. Thirteen of these trials gave results as dichotomous outcomes evaluating 3186 patients and there was no significant heterogeneity between the studies. There was a 8% relative risk reduction in the H pylori eradication group (95% CI = 3% to 12%) compared to placebo. The number needed to treat to cure one case of dyspepsia = 18 (95% CI = 12 to 48). A further three trials compared Bismuth based H pylori eradication with an alternative pharmacological agent. These trials were smaller and had a shorter follow-up but suggested H pylori eradication was more effective than either H2 receptor antagonists or sucralfate in treating non-ulcer dyspepsia. AUTHORS' CONCLUSIONS: H pylori eradication therapy has a small but statistically significant effect in H pylori positive non-ulcer dyspepsia. An economic model suggests this modest benefit may still be cost-effective but more research is needed.