The guideline of the Korean College of Helicobacter and Upper Gastrointestinal Research group for Helicobacter pylori infection was first produced in 1998, when definite indication for H. pylori eradication is early gastric cancer in addition to the previous indications of peptic ulcer (PUD) including scar lesion and marginal zone B cell lymphoma (MALT type). Though treatment is recommended for the relatives of a patient with gastric cancer, unexplained iron deficiency anemia, and chronic idiopathic thrombocytopenic purpura, a consensus treatment guideline is the treatment of PUD, MALToma, and gastric cancer in Korea. One- or 2-week treatment with proton pump inhibitor (PPI)-based triple therapy consisting of one PPI and 2 antibiotics, clarithromycin and amoxicillin, is recommended as the first-line treatment regimen. In the case of treatment failure, one or 2 weeks of quadruple therapy (PPI + metronidazole + tetracycline + bismuth) is recommended, whose eradication regimen was not different between Korea and Japan. Though the treatment regimen was similar between two nations, the Japanese government declared the inclusion of H. pylori eradication in patients with H. pylori-associated chronic gastritis, reaching the conclusion that the treatment guideline became quite different between Korea and Japan from February 21, 2013. The prime rationale of the Japanese extended treatment guideline for H. pylori infection was based on the drastic intention to prevent gastric cancer as well as the improvement of chronic gastritis-associated functional dyspepsia based on their findings that H. pylori eradication might decrease gastric cancer incidence as well as mortality. In this review, the discrepancy between the Korean and Japanese treatment guidelines will be explained; why and how?