In this study we want to proof that the use of a new narrow-band imaging (NBI) tool (Exera III, Olmpus) is capable to rise accuracy of optically ascertained diagnoses of colonic polyps. NBI is a light filter tool which can be activated by pressing a button at the endoscope. NBI function leads to an endoscopic picture which appears blue and enables endoscopists to better assess surface structures and vascular patterns.