In the present study we evaluated the efficacy and tolerability of two different therapeutic schedules in eradicating Helicobacter pylori. Forty-six consecutive patients (suffering from either peptic ulcer or non-ulcer dyspepsia) with helicobacter pylori infection were randomly allocated to one of the following two groups: group 1 (n = 23) 2 weeks of treatment with bismuth subcitrate tablets (120 mgx4) + amoxycillin capsules (500 mgx4) + metronidazole tablets (250 mgx4); group 2 (n = 23) 2 weeks of treatment with amoxycillin capsules (500 mgx4) + metronidazole tablets (250 mgx4). Endoscopy, histology and bacterial culture were performed at entry, and 30 and 90 days after treatment. Two group 1 patients and one group 2 patient did not complete the treatment. Successful eradication was obtained in 20/21 (95%) patients treated with triple therapy (group 1) and in 17/22 (77%) patients treated with double therapy (group 2) (p = 0.2). Side-effects occurred in 9/21 (43%) patients of group 1 and in 9/22 (41%) patients of group 2 (p = 0.9). These were all self-limiting and required no specific treatment. These data suggest that combined therapy with amoxycillin and metronidazole, with or without bismuth subcitrate, represents a safe and effective therapeutic approach for the treatment of Helicobacter pylori infection. In our series, triple therapy determined a numerically higher eradication rate than double therapy.