Aim To evaluate whether eradication therapy is more effective in peptic ulcer disease (PUD) than in non-ulcer dyspepsia (NUD). Methods We retrospectively studied 481 patients with NUD (183 patients) or PUD (298 patients) infected with Helicobacter pylori included in several prospective clinical trials. Three eradication regimens were given: (1) proton pump inhibitor (PPI) plus clarithromycin, plus either amoxycillin or metronidazole for 7 days (297 patients); (2) ranitidine bismuth citrate (RBC) plus clarithromycin plus amoxycillin for 7 days (79 patients); and (3) RBC plus clarithromycin plus amoxycillin plus metronidazole for 5 days (105 patients). H. pylori eradication was defined as a negative C-13-urea breath test 4 weeks after completing treatment. Results H. pylori eradication rates were 82% (95% Cl 78-87%) with PPI plus two antibiotics for 7 days, 85% (95% Cl 75-91 %) with RBC plus two antibiotics for 7 days, and 91% (95% Cl 86-97%) with RBC plus three antibiotics for 5 days (P < 0.05 compared with the first regimen). Overall, the H. pylori eradication rate in patients with NUD was 78% (95% Cl 71-84%), while in patients with PUD it was 89% (95% Cl 86-93%) (P < 0.001). Both the combination of PPI plus two antibiotics for 7 days and the combination of RBC plus three antibiotics for 5 days were more effective in PUD than in NUD patients. However, RBC plus clarithromycin plus amoxycillin for 7 days was equally effective in both diseases. RBC plus two antibiotics for 7 days achieved better results than the same therapy with PPI only in NUD patients (84% v. 59%, P < 0.01), but both regimens were similar when prescribed in PUD patients (86% v. 88%). In the multivariate analysis, the type of therapy, the diagnosis (NUD v. PUD), and the product variable of therapy (with RBC plus 2 antibiotics for 7 days) and diagnosis (interaction variable) were the only variables that influenced H. pylori eradication. The odds ratio (OR) for the effect of RBC versus PPI plus two antibiotics for 7 days in patients with NUD was 4 (95% Cl 1.7-9.7; P < 0.01), whereas in patients with PUD no statistical significance was achieved (OR 0.79; 95% Cl 0.2-3.9). Conclusion Overall, H. pylori eradication therapy is more effective in PUD than in NUD patients. This advantage of eradication therapies in PUD patients seems to be observed with 7-day PPI-based triple regimens, and with 5-day RBC-based quadruple therapy, while the 7-day RBC-based triple regimen seems to be equally effective in both diseases. (C) 2001 Lippincott Williams & Wilkins.