BACKGROUND There are few series reporting efficacy of seven-day therapy with omeprazole, amoxicillin and clarithromycin for cure of Helicobacter pylori infection in Spain. The aim of the present study was to evaluate the efficacy of this treatment to eradicate H. pylori infection. METHODS One hundred consecutive patients with peptic ulcer disease and H. pylori infection were evaluated for eradication therapy between January and November 1996. Four of them were excluded because of reported penicillin allergy. The remaining 96 patients received a seven days course of omeprazole 20 mg/12h, clarithromycin 500 mg/12h and amoxicillin 1 g/12h. The efficacy of the treatment was evaluated at 2-4 months after therapy either by endoscopic biopsy or by 13C urea breath-test. RESULTS Seventy-eight patients were found to be cured at the control evaluation. Intention to treat analysis showed a cure rate of 81.3% (95% CI: 74-89%). Per protocol analysis showed a cure rate of 85.7% (95% CI: 79-93%)--78 out of 91 patient who returned for follow-up-. Compliance with the treatment was good in 94.5% of patients. Five patients presented mild side effects (diarrhea, abdominal pain, oral candidiasis and metallic taste). None of them had to interrupt the treatment. CONCLUSIONS Seven-day therapy with omeprazole, amoxicillin and clarithromycin achieves a 85% cure rate of H. pylori infection in our area.