Rupture of the spleen after colonoscopy is a rare but dangerous complication; up to now only a few cases have been reported in the literature. This complication is more frequent in patients who have previously undergone abdominal surgery and after operative colonoscopies. This case report describes a 64-year-old man who complained of abdominal pain and dyspnoea some hours after a colonoscopy. Laboratory exams showed anaemia; the patient also developed hypotension and tachycardia; a CT scan revealed a splenic laceration with haemoperitoneum. A laparotomic splenectomy was successfully carried out.