Complications due to diagnostic colonoscopy are very rare. Perforation is the most frequent colon-related event. So far only ten cases of acute appendicitis after colonoscopy have been reported in the literature. We present the case of a 79-year-old man who developed acute appendicitis after diagnostic colonoscopy. Diagnosis was aggravated by the fact that in the patient's history an appendectomy had been performed 65 years earlier. Because of the rarity of this event it is doubtful whether the endoscopic examination was causal or coincidental. However, in cases of pain after colonoscopy, appendicitis has to be included in the differential diagnosis.