INTRODUCTIONAt present, 1-week proton pump inhibitor-based triple therapy is the most recommended regimen for the treatment of H. pylori infection.1 From the ®rst successful experience of Bazzoli and his group, 2 other clinical trials, both small and large 3,4 have con®rmed the ef®cacy of this short-term multiple treatment. In recent years, however, the novel compound ranitidine bismuth citrate (RBC) has been shown to be an effective antiHelicobacter drug when combined with clarithromycin for 14 days.5 In relation to the good results of 1-week proton pump inhibitor-based triple therapy, we have recently shown that shortening the treatment with RBC plus low-dose clarithromycin and metronidazole to SUMMARY Background: Ranitidine bismuth citrate (RBC) co-prescribed with clarithromycin and metronidazole for 1 week has been shown to be an effective eradicating regimen for Helicobacter pylori. Aim: To determine the optimal duration of this regimen. Methods: A series of 165 dyspeptic patients were recruited for this randomized, open, parallel-group study. They were subdivided into three groups receiving RBC 400 mg b.d. plus clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. for three different periods (4, 7 and 10 days). H. pylori infection was assessed by the concomitant positivity of CLO-test and histology performed at the pre-entry endoscopy. The bacterium was considered eradicated on the basis of a negative 13 Curea breath test performed at least 28 days after the completion of treatment. Results: The three subgroups were well matched and 16 patients dropped out of the study for many reasons (six