Helicobacter pylori eradication remains a challenge for physicians. Sequential, concomitant and the hybrid regimens have been proposed as novel, more effective therapies. We compare the efficacy of these therapies. Dyspeptic patients referred for upper endoscopy with H. pylori infection were enrolled. Patients were randomized to receive: (a) sequential therapy - 20 mg omeprazole and 1 g amoxicillin for 5 days, followed by 20 mg omeprazole, 500 mg clarithromycin and 500 mg tinidazole for the successive 5 days; (b) concomitant therapy - 20 mg omeprazole, 1 g amoxicillin, 500 mg clarithromycin and 500 mg tinidazole for either 5 days (5 day concomitant) or 14 days (14 day concomitant); or (c) hybrid therapy - 20 mg omeprazole and 1 g amoxicillin for 7 days, followed by 20 mg omeprazole, 1 g amoxicillin, 500 mg clarithromycin and 500 mg tinidazole for the successive 7 days. All drugs were given twice daily. Bacterial eradication was checked by using a [(13)C]urea breath test. In 'intention-to-treat' analysis, sequential therapy achieved the highest eradication rate, which was higher than that of 5 day concomitant therapy (90 vs 78.1 %; P = 0.02). The success rate did not statistically differ among the sequential and either 14 day concomitant (90 vs 86.3 %; P = not significant) or hybrid therapies (90 vs 82.7 %; P = not significant). The 10 day sequential, 14 day concomitant and 14 day hybrid therapies, but not the 5 day concomitant regimen, achieved similarly high eradication rates. The lower therapeutic cost coupled with the lower number of tablets needed would favour the sequential therapy as the first-line H. pylori treatment in clinical practice.