In a prospective randomised multicenter setting we plan to conduct colonoscopy in 380 patients. Half of the patients will be examined without use of NBI (control arm). In these cases colonoscopists will assess optical diagnosis of polyps without turning on the NBI tool. If polyps are detected in patients belonging to the intervention arm NBI will be used and optical diagnosis will be determined using the NICE (NBI International Colorectal Endoscopic) classification. All polyps will be resected and send to pathology for further microscopic assessment. After completing the trial we aim to compare accuracy of the optical diagnosis in both groups. Our hypothesis is, that by using the new NBI tool accuracy (accordance between optical and histopathological diagnosis) can be increased from 78% to 90%.