The investigators aimed to compare the eradication rates of sequential therapy for 10 days versus triple therapy for 14 days

Inclusion Criteria:

• Patients are aged greater than 20 years who have H. pylori infection without prior eradication therapy and are willing to receive the sequential therapy will be eligible for enrollment.
• Written informed consents will be obtained from all patients prior to enrollment.

Exclusion Criteria:

Patients will be excluded from the study if any one of the following criteria is present:

• children and teenagers aged less than 20 years,
• history of gastrectomy,
• gastric malignancy, including adenocarcinoma and lymphoma,
• previous allergic reaction to antibiotics (amoxicillin, clarithromycin, levofloxacin, metronidazole) and prompt pump inhibitors (lansoprazole), - contraindication to treatment drugs,
• pregnant or lactating women,
• severe concurrent disease
• Patients who cannot give informed consent by himself or herself.