<p><b>OBJECTIVE</b>To investigate the efficacy of repeat transurethral resection of tumor in patients with non-muscle invasive bladder cancer.</p><p><b>METHODS</b>From March 2004 to August 2008, 462 patients (350 males, 112 females, aged from 35 to 83 years old) with non-muscle invasive bladder cancer, were evaluated according to tumor stage, grade and muscle or no muscle tissue in initial transurethral resected sample. One hundred and twenty-five patients underwent repeat transurethral resection of bladder tumor within 4 to 6 weeks after initial resection. Of these 125 patients 49 were Ta, 76 were T1, 58 were low grade carcinoma, 67 were high grade carcinoma and 30 were not found presence of muscle tissue in initial resected sample in patients with T1 stage.</p><p><b>RESULTS</b>Of the 125 cases, 34.4% (43/125) had residual tumor and 65.6% (82/125) had no tumor on repeat transurethral resection. Of 43 cases with residual tumor 35 had non-muscle invasive tumor including 15 in Ta and 20 in T1. The patients with high grade carcinoma had more residual tumor than those with low grade carcinoma (P < 0.05). The patients with muscle tissue in initial transurethral resected sample had fewer residual tumor than those without (P < 0.05). Twelve cases (9.6%) were understated at initial resection. Six cases (4.8%) had bladder perforation and 7 (5.6%) had bleeding during repeat transurethral resection. All cases were followed up for 3 to 56 months (median 26 months), 37.2% (16/43) patients with residual tumor in repeat transurethral resection had recurrence while only 12.2% (10/82) without residual tumor in repeat transurethral resection did (P < 0.05).</p><p><b>CONCLUSIONS</b>Routine repeat transurethral resection is advised to non-muscle invasive bladder cancer patients with T1 tumor or high grade carcinoma or no muscle tissue in initial transurethral resected sample within 4 to 6 weeks after initial resection. Repeat transurethral resection could increases the stage accuracy.</p>