Although colonoscopy is commonly performed, it is an invasive procedure that might produce complications such as hemorrhage and perforation. Colonic perforation is an abdominal emergency with high mortality requiring surgical intervention. Sometimes non-surgical teatment can be applied when perforation is small sized, located in the retoperitoneal spaces or surgical approach is impossible. We are reporting a case of colon perforation in 64-year-old female patient. The patient visited our hospital with symptoms of dizziness and dyspnea. She was anemic and we planned to find the possible cause of anemia. Rectal perforation was developed during the diagnostic colonoscopy. However the operation was not applicable due to arrhythmia and cardiogenic shock. Therefore endoscopic clipping was done at the perforation site. Afterwards nasogastric decompression, intravenous antibiotics and total parenteral nutrition were applied. She was treated successfully without any complications. (Korean J Gastrointest Endosc 2003;26:232235)