The exams will be performed back to back with a standard colonoscope and an ETMI colonoscope provided by Olympus. The order of the first and second procedure will be randomized according to a list prepared by the statistician using randomly permuted blocks to ensure equal numbers of patients are randomized to the two groups. All patients will be sedated with meperidine or fentanyl and midazolam to achieve conscious sedation. Each procedure will be preformed by a different endoscopist. The endoscopist will be either the P.I. supervised by a GI staff physician or solely by one of the five GI staff physicians. During the initial colonoscopy all visualized polyps will be noted, photographed, and removed. When the ETMI colonoscope is used, all polyps will be photographed using these modes (HDWL, HDNBI). The NBI portion of the exam will be performed using the MB-046 cap to further enhance stabilization of the focal length of the colonoscope.