Members of the American Society of Colon and Rectal Surgeons were polled regarding complications of colonoscopy and polypectomy. Sixty per cent of the members responded. One hundred sixty-two surgeons were found to be performing colonoscopy, and this paper presents the accumulated data on complications. A total of 20,139 colonoscopies were performed, with 12,746 diagnostic procedures and 7,393 polypectomies. The overall complication rate was 0.4 per cent with diagnostic colonoscopy and 1.8 per cent with polypectomy. Based upon these complications, guidelines in regard to history, preparation, and technique of colonoscopy and polypectomy are discussed.