Abstract Background Narrow band imaging (NBI) is an optical enhancement technology that filters white light into two bandwidths of illumination centered on 415 nm (blue) and 540 nm (green). NBI cystoscopy can increase bladder cancer (BCa) visualization and detection at the time of transurethral resection (TUR). NBI may therefore reduce subsequent relapse following TUR. Objective Assess the impact of NBI modality on 1-yr non–muscle-invasive BCa (NMIBC) recurrence risk. Design, setting, and participants Consecutive patients with overt or suspected BCa were included in a prospective study powered to test a 10% difference in 1-yr recurrence risk in favor of cases submitted to NBI TUR. Excluding patients with muscle-invasive BCa, negative pathologic examination, or without follow-up, the study population was composed of 148 subjects randomized from August 2009 to September 2010 to NBI TUR (76 cases) or white light (WL) TUR (72 cases). Intervention TUR was performed in NBI or standard WL modality. Measurements The 1-yr recurrence risks in NBI or WL TUR groups were compared using odds ratio (OR) point and interval estimates derived from logistic regression modeling. Results and limitations The 1-yr recurrence-risk was 25 of 76 patients (32.9%) in the NBI and 37 of 72 patients (51.4%) in the WL group (OR = 0.62; p = 0.0141). Simple and multiple logistic regression analyses provided similar OR points and interval estimates. Conclusions TUR performed in the NBI modality reduces the recurrence risk of NMIBC by at least 10% at 1 yr.