OBJECTIVES:  In Japan, cancer screening is not covered by health insurance, but is provided and paid for by local governments. In clinical practice, asymptomatic subjects have undergone upper gastrointestinal endoscopy as cancer screening that has been charged to health insurance. In order to file a claim for health insurance, the actual name of the disease must be reported even for an asymptomatic person. The number of upper gastrointestinal endoscopic examinations for asymptomatic persons in clinical practices was estimated based on the national health insurance data and the national patients’ survey. METHODS: There were 501,002 endoscopic examinations and 178,200 persons with gastric diseases in 2008. The appropriate numbers of endoscopic examinations were calculated based on the following models. At admission, an endoscopic examination was performed once for each patient. For outpatient cases at the first visit, an endoscopic examination was performed once for gastric and esophageal cancer patients and 0.5 times for patients with another upper gastrointestinal disease. For outpatient follow-up, patents were examined once a year if they had a gastric cancer or an esophageal cancer and 0.5 times a year if they had another upper gastrointestinal disease. A sensitivity analysis of the number of endoscopic examination of outpatients with another upper gastrointestinal disease was performed by changing the number of examinations from 0.1 to 0.8 times for outpatients both at the first visit and at follow-up. The difference between the estimated and observed numbers was defined as representing the number of inappropriate endoscopic examination performed for asymptomatic patients. RESULTS: Using the initial assumptions, asymptomatic patients accounted for 30.8% of all cases undergoing upper endoscopy. On sensitivity analysis, this ranged from 2.2% to 69.0%. CONCLUSIONS: The results suggest that a substantial number of upper gastrointestinal endoscopies are performed for asymptomatic patients in clinical practice, and this cannot be ignored.