Background: A number of triple drug regimens using proton pump inhibitors and two antibiotics have been evaluated in the West and reported to achieve Helicobacter pylori eradication rates of over 90%. In developing countries however, these combinations have neither been well evaluated, nor the optimum treatment for H, pylori infection well defined. Aim: To compare the combination of a proton pump inhibitor with a nitroimidazole and another antibiotic in eradicating H, pylori infection and healing duodenal ulcer. Methods: Sixty consecutive patients with active duodenal ulcer who were positive for H, pylori (by rapid urease test and C-14-urea breath test) were randomized into three treatments groups: (1) LAS (n = 21): lansoprazole 30 mg o.m., amoxycillin 500 mg q.d.s. and secnidazole 2 g on alternate days for 2 weeks; (2) LCS (n = 18): lansoprazole 30 mg o.m., clarithromycin 500 mg b.d. and secnidazole 2 g on alternate days for 1 week; (3) LPS (n = 21): lansoprazole 30 mg o.m., pefloxacin 400 mg o,m, and secnidazole 2 g on alternate days for 2 weeks. Urease and breath tests were performed at 0, 6 and 12 weeks to check for H. pylori eradication, Results: Intention-to-treat eradication rates were as follows: LAS 86%, LCS 83%, LPS 71%; the overall ulcer healing rate was 90% at 6 weeks. Conclusions: High H. pylori eradication rates were achieved using the amoxycillin- and clarithromycin-based therapies. Fewer side-effects, better compliance and low cost favoured the amoxycillin-based therapy.