Introduction: The detection of adenomas is the basic goal for colorectal cancer screening programs; therefore, every possibility to improve the adenoma detection rate is valuable. Aim: To answer the question of whether narrow-band imaging (NBI) can enhance detection quality in screening for colonoscopy. Material and methods: A group of 533 patients (202 men: 331 women; average age: 56.1 years) included in a colorectal cancer screening program were randomised into two groups (NBI n = 266 and white light (WL) n = 267). Five hundred and twentyseven patients were finally included in the assessment. Examinations were performed by three experienced colonoscopists. The NBI was used only at the withdrawal of the instrument. Results: Comparing WL and NBI colonoscopies, differences in the mean number of detected polyps per patient (1.36 ±2.79 WL vs. 1.65 ±2.11 NBI; p = 0.012), polyp detection rate (PDR) (48.5% WL vs. 57.2% NBI; p = 0.049), PDR for polyps ≤ 5 mm (44.7% WL vs. 54% NBI; p = 0.033), and PDR for left-sided polyps (43.3% WL vs. 52.7% NBI; p = 0.033) were observed. The difference in adenoma detection rate (ADR) as well as in adenomas/patient was not significant. Narrow-band imaging enhanced significantly one of three operators’ ADR (15.6% WL vs. 25.7% NBI; p = 0.038). Conclusions: It seems that NBI improves only detection of hyperplastic polyps, especially those that are diminutive and left-sided. However, after analysis of particular endoscopists, it can clearly be seen that some of them may benefit from NBI.