OBJECTIVE To determine the impact of Narrow Band Imaging (NBI) in detection and resection of tumors during transurethral resection of bladder cancer. MATERIALS AND METHODS This was a single center randomized prospective interventional study with a sequential intervention design. Patients with bladder tumors were randomized into 2 arms where they were resected under white light (WL) first followed by NBI in arm A, or NBI followed by WL in arm B. The number of patients in whom additional lesions were detected by the second light source, in both arms, was analyzed. The feasibility of initial resection of tumor under NBI was also studied. RESULTS A total of 110 patients were randomized. Of 54 patients in arm A (WL first) additional lesions were identified at the second look in 20 patients (37%). In contrast, of 56 patients in arm B (NBI first), additional lesions were identified in 5(9%) patients. This difference of 28% was statistically significant (P value CONCLUSION Narrowband imaging is superior to WL in the detection of tumors, thus allowing a more complete resection. However, initial resection under NBI is difficult due to poor visibility, especially for high-risk tumors.