The aims of this pilot study were: (i) to compare the efficacy of low-dose clarithromycin (250 mg twice daily) for 1 or 2 weeks; and (ii) to evaluate possible therapeutic advantages in associating the low-dose clarithromycin with an anti-secretory agent or tripotassium dicitrate bismuthate (De Nol; Yamanouchi Pharm, Corugate Milano, Italy). A prospective, randomized, open trial was carried out on consecutive outpatients with dyspeptic symptoms and Helicobacter pylori infection. We enrolled 129 patients in one of the following schedules: (A) De Nol 120 mg q.i.d., clarithromycin 250 mg b.i.d. and metronidazole 250 mg q.i.d. for 2 weeks; (B) omeprazole 20 mg b.i.d., clarithromycin 250 mg b.i.d. and metronidazole 250 mg q.i.d. for 2 weeks; or (C) omeprazole 20 mg b.i.d., clarithromycin 250 mg b.i.d. and metronidazole 250 mg q.i.d. for 1 week. Results were evaluated by Per Protocol (PP) and Intention-To-Treat analysis (ITT). Eradication rate was 100% after treatment A, 92.6% after treatment B and 86.5% after treatment C by PP and 83.3, 75.7, and 68.1%, respectively by ITT. Side effects were reported by 16 subjects: 26.6% in group A; 9.1% in group B; and 7.5% in group C; in two cases side effects led to the withdrawal of the treatment. In conclusion, 500 mg clarithromycin per day in association with omeprazole and metronidazole, for 1 week gave comparable results to the same schedule for a 2 week period. The use of clarithromycin with bismuth and metronidazole produced a therapeutic gain compared with both of the anti-secretory schedules, although this was not statistically significant.