The bioengeneering technological development associated with new medical information transformed colonscopy today in one of the most complete method of investigation on colorrectal diseases. The authors aim to describe the use of colonoscopy as a diagnostic and therapeutic method, its main indications and limitations. The wide utilization of colonoscopy as therapy is emphasized in the polipectomy, the identification of bleeding areas and the hemostasy. Some intervening facts are discussed as copious bleeding, perfuration and post polipectomy syndrome. Finally, the authors report the low morbidity and mortality rates in their personal experience with colonoscopy during the last decade.