We evaluated the use of narrow-band imaging (NBI) cystoscopy for the detection of bladder cancer and analyzed its diagnostic efficacy in cases of carcinoma in situ (CIS) and in cases with known urine cytology results. A prospective controlled study of NBI was conducted in 104 consecutive patients with definite or suspected bladder cancer. Transurethral targeted biopsies were performed after white light imaging (WLI) and NBI cystoscopy, and the histologic outcomes were compared. A total of 313 biopsies were taken, including 161 from sites identified as potentially abnormal by NBI and/or WLI cystoscopy, and 152 from apparently normal sites. The percentage of malignancies in the sites identified only by NBI was 55.7% (39/70 places). In 26.9% of patients (28/104), bladder tumors were detected only by NBI. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio of a negative test (NLR) for the detection of bladder tumors using NBI in all patients were 92.7%, 70.9%, 63.4%, 94.7%, and 0.10, respectively. The sensitivity, specificity, PPV, NPV, and NLR for the detection of CIS using NBI were 89.7%, 74.5%, 78.8%, 87.2%, and 0.14, respectively. The sensitivity, specificity, PPV, NPV, and NLR for the detection of bladder tumors using NBI in patients with positive vs negative urine cytology were 85.4% vs 98.4%, 75.7% vs 66.3%, 61.2% vs 64.5%, 92.0% vs 98.5%, and 0.19 vs 0.02, respectively. NBI is a simple and effective method for identifying bladder tumors including CIS without the need for dyes because of its high sensitivity, high NPV, and low NLR.