Background and study aims: It has been proposed that the use of narrow-band imaging (NBI) for real-time histological assessment to determine postpolypectomy surveillance intervals is a costeffective approach to the management of diminutive polyps. However, significant discrepancies in NBI performance have been observed among endoscopists; hence, professional societies recommend training, monitoring, and auditing. The aim of the present study was to evaluate the performance of real-time optical diagnosis for diminutive polyps after the inclusion of this approach in an internal quality assurance program, in order to assess its applicability in clinical practice. Patients and methods: Four endoscopists attended periodic training sessions on NBI assessment of polyp histology before and during the study. Performance was audited and periodic feedback was provided. The accuracy of high-confidence NBI evaluation for polyps =5mmin predicting surveillance intervals according to the European and US guidelines, and the negative predictive value (NPV) for adenoma in the rectosigmoid were calculated and compared with recommended thresholds (90% agreement and 90% NPV, respectively). Results: Overall, 284 outpatients (mean age 61.3± 18.2 years; 63% males) were enrolled. A total of 656 polyps were detected, 465 of which (70.9%) were diminutive (70.5% adenomas). Sensitivity, specificity, positive and negative predictive values, and accuracy of high-confidence NBI predictions for adenoma in diminutive lesions were 95.3%, 83.5%, 93.5%, 87.6%, and 91.9%, respectively. High-confidence characterization of diminutive polyps predicted the correct surveillance interval in 95.8% and 93.3% of cases according to European and American guidelines, respectively. NPV for adenoma in the rectosigmoidwas 91.3%. Conclusions: For community settings in which endoscopists are adequately trained and performance is periodically audited, real-time optical diagnosis for diminutive polyps is sufficiently accurate to avoid postpolypectomy histological examination of resected lesions, or to leave rectosigmoid hyperplastic polyps in place. [ABSTRACT FROM AUTHOR]