Colonoscopy is the gold standard in diagnosis of colorectal diseases. It is generally a safe procedure with low complication rate. Splenic rupture is a very rare complication of colonoscopy. The case presented here, is a 57 years old male patient with complaint of hematochesia. He had colonoscopy and diagnosed as sigmoid colon tumor. After colonoscopy he had the findings of acute abdomen. At the operation splenic rupture was detected and he had undergone splenectomy with subtotal colectomy for the sigmoidal tumor. Splenic rupture is very rare but fatal complication of colonoscopy. In the management of patients with post-colonoscopy abdominal pain splenic injury should be kept in mind.