Splenic injury following colonoscopy is extremely rare. We report a 75-year-old woman and a 35-year-old woman who presented to the emergency room with left upper quadrant and left shoulder pain following colonoscopy. Both patients were diagnosed by computed tomography (CT) with splenic injuries and hemoperitoneum. One patient was successfully managed conservatively, and one patient needed emergent open splenectomy. The possibility of splenic injury should be considered in postcolonoscopy patients with left upper quadrant or left shoulder pain.