Objective To evaluate the diagnostic efficacy of non-magnified NBI in distinguishing neoplastic from non-neoplastic colorectal polyps,using a simple classification system(NBI international colo-rectal endoscopic[NICE]classification).Methods A total of 181 lesions detected by white light colonosco-py were enrolled in this prospective study.Each lesion was assessed by NBI,and the histology was predicted according to characteristics of lesion color,microvascular architecture,and surface pattern.The results were compared with actual histologic findings.Results The diagnostic sensitivity,specificity,PPV,NPV,and accuracy of NBI were 95. 8%(114/119),91. 9%(57/62),95. 8%(114/119),91. 9%(57/62),and 94. 5%(171/181),respectively.Diagnostic accuracy was 90. 0%(72/80)in the 1 to 5 mm group,95. 9%(47/49)in the 6 to 9 mm group,98. 1%(51/52)in the more than 10 mm group,with no statistically sig-nificant differences(P=0. 175).The sensitivity,specificity,PPV,NPV,and accuracy of NBI for diminu-tive rectosigmoid neoplasms were 87. 5%(14/16),95. 2%(20/21),93. 3%(14/15),90. 9%(20/22), and 91. 9%(34/37).Conclusion NICE classification with non-magnified NBI is effective in distinguishing neoplastic from non-neoplastic colorectal lesions. Key words: Colorectal neoplasms ; Diagnosis ; Narrow-band imaging ; NICE classification ;