Retroflexion to evaluate the rectal vault provides significant additional information compared with standard forward view of the rectum. The procedure is easily performed with rare complications and is well tolerated by patients. We describe the first case of a large oval rectal perforation after retroflexion of the colonoscope in a healthy rectum during a follow-up colonoscopy, immediately closed with the endoloop/clips technique. The patient had an uneventful course and was discharged after 5 days. At his 2-month follow-up visit he remained asymptomatic and endoscopy revealed complete healing of the perforation.