Aim: to present our experience in eradicating Hp in three consecutive trials performed between 1995 and 1999. Methods: 320 duodenal ulcer outpatients have been enrolled in three open, prospective controlled trials. Hp infection was confirmed by Giemsa stain and Rut. In Trial I, 52 cases received 20 mg omeprazole+2x250 mg clarithromycin+2x500 mg tinidazole (OCT), 48 patients were given 20 mg omeprazole, 2x1000 mg amoxicillin+2x500 mg metronidazole (OAM) for 7 days; in Trial II, 48 cases received 40 mg pantoprazole+2x1000 mg amoxicillin+2x500 mg clarithromycin (PAC) for 7 days and 5l cases 2x400 mg ranitidin bismuth citrate+2x500 mg clarithromycin for 14 days (RBC-C); in Trial III, 60 cases were treated with 2x30 mg lansoprazole+2x250 mg clarithromycin+2x500 mg metronidazole and 6l patients received 2x400 mg ranitidin bismuth citrate+2x250 mg clarithromycin+2x500 mg metronidazole (RBC-CM). The patients were controlled within 4-6 weeks by endoscopy in trials I-II and 1 3 C-urea breath test in trial III. Results: Eradication rates on ITT/PP basis were: OCT: 72.3/80.2% vs OAM 51.2/63.5% (P=0.02/P=0.03); PAC: 80.8/88.3% vs RBC-C 80.3/85.4% (P=0.65/0.67) and LCM 78.3/92.1% vs RBC-CM 78.7/90.5% (P=0.86/P=0.93). Side effects occurred in 5.2, 8.6, 9.5, 14.5, 13.5 and 18.3% of the cases. Conclusion: Regimens using 2xl PPI or RBC+2 antibiotics for l week proved to be the most effective for Hp eradication in duodenal ulcer patients.