Helicobacter pylori (H. pylori) infection has been associated with a development of atrophic gastritis and intestinal metaplasia. H. pylori related atrophic gastritis and intestinal metaplasia have been regarded as pre-malignant lesion. However, the role of H. pylori eradication treatment in the reversibility of atrophic gastritis and intestinal metaplasia has not been clearly defined. The aim of the present study was to investigate the relationship between H. pylori eradication and the reversibility of atrophic gastritis and intestinal metaplasia in Korean patients.

It is a prospective, case-control study to compare the status of atrophic gastritis and intestinal metaplasia from the patients who undergo H. pylori eradication treatment or not. After enrollment, each patient will be receive annual surveillance upper gastrointestinal endoscopy. The present investigators will monitor the status of atrophic gastritis and intestinal metaplasia annually and finally compare the reversibility of them.

Inclusion Criteria:

- Patients who diagnosis of H. pylori infection

• Patients presenting with H. pylori related gastrointestinal disease and/or
• Patients do not have H. pylori related gastrointestinal disease. But, want H. pylori eradication

Exclusion Criteria:

- Age under 18 years Previous eradication treatment for H. pylori Patients who took any drug which could influence the study results such as proton pump inhibitor, antibiotics within 4 weeks History of gastrectomy Advanced gastric cancer or other malignancy Abnormal liver function or liver cirrhosis Abnormal renal function or chronic kidney disease Other severe concurrent diseases Previous allergic reactions to the study drugs Pregnant or lactating women

Patients who have H. pylori related gastrointestinal disease and/or Patients who do not have H. pylori related gastrointestinal disease. But, want H. pylori eradication