The aim of this study is to evaluate Sequential therapy versus hybrid therapy for helicobacter pylori eradication.Inclusion criteria: age more than 18 years and less than 80 years with duodenal or gastric ulcers; duodenal or gastric erosions and helicobacter pylori positivity. Exclusion criteria: Previous history of receiving any H.pylori eradication regimen, Taking H2 blocker, proton pump inhibitor, Bismuth or Antibiotics during the 2 weeks prior to the study, Taking anticoagulants, ketoconazole or corticosteroids, History of gastric or esophageal surgery, Severe cardiovascular, pulmonary or endocrine disease, Renal failure, Hepatic diseases, Malignancies, Alcoholism, Pregnancy or breast feeding. 296 patients with PUD(peptic ulcer disease) in whom H.pylori infection has been documented by rapid urease test or pathology will be enrolled in the study. The patients will be randomly received one of following interventions: 1) Hybrid: [pantoprazole 40mg (BD) + Amoxicillin 1g (BD)] x2weeks + Clarithromycin 500mg (BD) and Tinidazole 500mg (BD) during secon dweek. 2) Sequential : Pantoprazole 40mg (BD) for 10 days + Amoxicillin 1g (BD) just during the first 5 days + Clarithromycin 500mg (BD) and Tinidazole 500mg (BD) both just during the second 5 days in control group. Patients will be visited after the treatment course to be asked about their compliance to treatment and side effects. H pylori eradication that is primary end poin will be tested at least 8 weeks after the treatment course using C14-UBT (14-carbon urea breath test).