Narrow band imaging (NBI) is an imaging technique that allows a better definition of capillary pattern and improves the contrast between adenomas and the surrounding mucosa. Conflicting data exist on the ability of NBI in to improve detection of colonic neoplasm; the impact of NBI is being tested in several screening scenarios. The investigators evaluated whether the routine use of NBI, compared to white light (WL), during the withdrawal phase of screening colonoscopy improved adenoma detection.