BACKGROUND/AIMS: The decisive factors influencing the eradication of H. pylori still remain unclear To identify such factors, we investigated the clinical characteristics and antibiotic resistance of patients. METHODS: Patients with H. pylori infection were treated with dual or triple regimens. Eradi cation rates were analyzed on the basis of clinical factors, endoscopic factors and antibiotic resistance RESULTS: Sixty-three H. pylori infected patients were enrolled (mean age 49.4). The eradication rate was significantly higher in compliant patients (71.9%) than in non-compliant patients (20%). Other clinical and endoscopic factors did not significantly influence the outcome of treatment. In 42 isolated strains, metronidazole resistance (MIC>8 microgram/mL) was observed in 35.7% of the strains and clari thromycin resistance (MIC>2 microgram/mL) was observed in 7.1%. The eradication rate in metronidazole resistant strains was 55.5%, which was lower than that in metronidazole sensitive strains (78.6%) The median value of metronidazole MIC in the group of successful eradication (0.94 microgram/mL) was significantly lower than that in the group of failed eradication (64.0 microgram/mL). CONCLUSIONS: Patient' s compliance for regimens seems to be the most important factor which affect H. pylori eradication Metronidazole resistance which is highly prevalent in our population may influence the efficacy of anti-H. pylori treatment regimen containing metronidazole.