Colonoscopy is a safe procedure performed routinely worldwide. Splenic rupture is a rare complication of colonoscopy with several reported cases since 1974. We report the first case of a complication in the Republic of Korea. The literature on this rare complication is also reviewed here, with focus on the analysis of risk, diagnosis, and treatment. A 77-year-old patient receiving oral aspirin underwent colonoscopy with polypectomy. After 24 hours, the patient experienced dizziness and hypotension. Colonoscopy was performed to exclude intestinal bleeding, which could be diagnosed with hemoperitoneum. A computed tomography scan showed copious abdominal free blood and a splenic rupture. An urgent splenectomy was performed, which was the recognized procedure of choice. Physicians should have greater awareness of the possibility of splenic rupture following colonoscopy in order to avoid delay of diagnosis and treatment for this life-threatening complication.