Background/Aim: Helicobacter pylori (H pylori) plays an important role in the pathogenesis of chronic gastritis, peptic ulcer disease, and gastric neoplasms . Therefore, it is necessary to select an effective regimen for H pylori eradication . The aim of this study was to compare the efficacy of two quadruple-therapy regimens-one with azithromycin and the other with metronidazole-for H pylori eradication in patients with dyspepsia. Materials and Methods: In this double-blind randomized clinical trial conducted in Rasoule-Akram Hospital in 2006, we included 60 patients (aged 15-70 years) who had dyspepsia and H pylori infection as diagnosed by upper gastrointestinal endoscopy and rapid urease test. Patients were randomly assigned to receive a quadruple-therapy regimen for 2 weeks: 1) the MAO-B group (n = 30) received metronidazole 500 mg b.i.d, amoxicillin 1g b.i.d, omeprazole 20 mg b.i.d, and bismuth 240 mg b.i.d and 2) the AAO-B group (n = 30) received azithromycin 500 mg once daily for 1 week and amoxicillin 1g b.i.d, omeprazole 20 mg b.i.d, and bismuth 240 mg b.i.d for 2 weeks). H pylori eradication was assessed by the rapid urease test (RUT) 2 months after the cessation of treatment . Results: H pylori was eradicated in 68% and 69% of patients in the MAO-B and AAO-B groups, respectively. There was no significant difference in H pylori eradication rates between the two groups (P = 0.939). Conclusion: No significant difference exists between the two quadruple-therapy regimens that were tested