The less frequent complications of colonoscopy include pneumothorax, pneumoperitoneum, emphysema of the retroperitoneum or of the subcutis, septicemia and injuries of visceral organs (mainly the spleen). Since the mid 1970 s more than 30 splenic injuries during colonoscopy have been described. Any cause of increased splenocolic adhesions (inflammatory bowel disease, pancreatitis or prior abdominal surgery) might be a predisposing factor for splenic injury during colonoscopy. Other contributing factors are techniques that result in a strong torsion of the spleno-colic ligament. Patients with left shoulder and abdominal pain, hypotension, and a drop in hemoglobin without rectal bleeding after colonoscopy should be suspected to have splenic injury. Many physicians are not aware of splenic injuries as a potential complication of colonoscopy. Therefore the diagnosis of splenic injury during colonoscopy is often described in the literature as delayed (hours until 10 days). Since a colonoscopic splenic injury can be fatal, this exceedindly rare event must be considered when a patient shows the above-mentioned symptoms and no signs of colon perforation.