Objectives: A recent randomized trial showed that 14-day sequential therapy containing high dose proton pump inhibitor was higher than 95% in the first line treatment. However, whether the 14-day sequential therapy is more effective than 10-day bismuth quadruple therapy remains unknown. Therefore, the investigators aimed to compare the eradication rates and long term re-infection rates of sequential therapy for 14 days versus bismuth quadruple therapy for 10 days in the second line treatment.