OBJECTIVES: The objective of this study was to investigate the incidence of complications (bleeding and perforation) with hospitalization from both upper and lower GI tract in Japanese population using a healthcare claims database (HDB). METHODS: All of the claims data of the patients who have a history of hospitalization due to complications from GI tracts between January 2011 and December 2012 were extracted from the HDB which holds about 1.8 million peoples’ claims data under employment-based health insurance. In order to identify upper and lower GI events precisely, we confirmed them when a diagnosis of a GI event in the claims (ICD-10 code) was accompanied by a record of examination and/or endoscopic or surgical treatment relevant to upper and lower GI complications. RESULTS: The total number of person-years at risk was 1.2 million person-years in 2012. The incidence rates in upper and lower GI events were 48 and 41 per 100,000 person-years, respectively. Twenty-one percent of the lower events originated in bleeding from hemorrhoid or related treatments (eg. hemorrhoidectomy). Age-group analyses in the upper vs. lower events, except those from hemorrhoid, were 27 vs. 17, 57 vs. 46 and 184 vs. 104 per 100,000 person-years in 20-39, 40-59, and 60+ years groups, respectively. Data from 2011 were consistent with these observations on the ratio of upper to lower GI events and the age-based incidence, indicating the robustness of the results.  CONCLUSIONS: This was the first study to investigate the incidence from both upper and lower GI complications with hospitalization in a real clinical setting in Japan using a single large data source. We confirmed that a number of GI events occurred in both upper and lower GI tract and the incidence rates of both events were increased with age in a real world setting.