BACKGROUND/AIMS: Low-dose aspirin therapy is widely used to prevent cardiovascular thrombotic events. However, the safety of low-dose aspirin therapy in the gastrointestinal tract is uncertain. Our aim was to evaluate endoscopic findings in patients taking low-dose aspirin. METHODS: Sixty-two patients who received 100 mg enteric coated aspirin daily more than 30 days were included in this study. Patients' medical records and endoscopic data were reviewed retrospectively. As controls, 70 of age- and gender-matched patients who received an endoscopy without gastrointestinal symptoms were employed. RESULTS: The overall prevalence of gastroduodenal mucosal injury was higher in the aspirin group than in the control group. Erosive gastritis was noted more frequently in the aspirin group than in the control group. However, the prevalence of ulcer was not different between the aspirin group and the control group. CONCLUSIONS: Patients treated with low-dose aspirin therapy are more likely to have endoscopic evidence of mucosal damage. Our study suggests that even a low-dose aspirin therapy can induce a gastroduodenal mucosal injury. In the future, a prospective randomized control study is needed.