BACKGROUND: Peptic ulcer disease is the cause for dyspepsia in about 10% of patients. 95% of duodenal and 70% of gastric ulcers are associated with Helicobacter pylori. Eradication of H pylori reduces the relapse rate of ulcers but the magnitude of this effect is uncertain. OBJECTIVES: The primary outcomes were the proportion of peptic ulcers healed initially and proportion of patients free from relapse following successful healing. Eradication therapy was compared to placebo or pharmacological therapies in H. pylori positive patients. Secondary aims included symptom relief and adverse effects. SEARCH STRATEGY: A search was undertaken according to the Cochrane Upper Gastrointestinal and Pancreatic Diseases Review Group module using CCTR, MEDLINE, EMBASE and CINAHL databases. Experts in the field and pharmaceutical companies were contacted. Abstract books between 1994 and 2002 were hand-searched. SELECTION CRITERIA: Randomised controlled trials of short and long-term treatment of peptic ulcer disease in H. pylori positive adults were analysed. Patients received at least one week of H pylori eradication compared with ulcer healing drug, placebo or not treatment. Trials were included if they reported assessment from 2 weeks onwards. DATA COLLECTION AND ANALYSIS: Data were collected on ulcer healing, recurrence, relief of symptoms and adverse effects. MAIN RESULTS: 59 trials were eligible. Data extraction was not possible in 7 trials, and 52 trials were included. In duodenal ulcer healing, eradication therapy was superior to ulcer healing drug (UHD) (34 trials, 3910 patients, relative risk [RR] of ulcer persisting = 0.66; 95% confidence interval [CI] = 0.58, 0.76) and no treatment (2 trials, 207 patients, RR = 0.37; 95% CI 0.26, 0.53). In gastric ulcer healing, no significant differences were detected between eradication therapy and UHD (13 trials, 1469 patients, RR = 1.32; 95% CI = 0.92, 1.90). In preventing duodenal ulcer recurrence no significant differences were detected between eradication therapy and maintenance therapy with UHD (4 trials, 319 patients, relative risk [RR] of ulcer recurring = 0.73; 95% CI = 0.42, 1.25), but eradication therapy was superior to no treatment (26 trials 2434 patients, RR = 0.19; 95% CI = 0.15, 0.26). In preventing gastric ulcer recurrence, eradication therapy was superior to no treatment (9 trials, 774 patients, RR = 0.31; 95% CI 0.19, 0.48). REVIEWER'S CONCLUSIONS: A 1 to 2 weeks course of H. pylori eradication therapy is an effective treatment for H. pylori positive peptic ulcer disease.