A total of 196 records of colonoscopic surgical complications were reviewed during a 12-year period. Perforation (183 patients) and haemorrhage (11) were the two main complications. Diagnosis of perforation was delayed in 58 per cent of patients. The sigmoid colon was the site of perforation in 72 per cent with evidence of peritoneal contamination in 59 per cent. Postoperative mortality rate of perforation was 12 per cent and was significantly related to a past history of medical disease and size of perforation. Postoperative morbidity rate was 43 per cent. There were two deaths after colostomy closure. The overall mortality rate of colonoscopic perforation requiring an emergency surgical procedure reached 14 per cent. Haemorrhage always occurred after endoscopic polypectomy; the postoperative course was uneventful in these patients.