Helicobacter pylori (H. pylori) infection causes atrophic gastritis (AG) and intestinal metaplasia (IM), which are known as the main precursor lesions of gastric cancer. The prevalence of AG and IM varies depending on countries, even it represents diverse results in the same nation. Usually AG is antecedent of IM, but the risk factors of AG and IM are not always the same. Furthermore, the management strategy of AG and IM has not been established, yet. However, eradication of H. pylori is very important to prevent the progression of AG and IM to gastric cancer. Therefore, early diagnosis of AG and IM is very important, especially in high incidence area of gastric cancer. However, as the endoscopic, histological, and serological diagnostic tool had a limitation, a multifactorial assessment is needed to ameliorate the diagnostic accuracy of AG and IM.