Objectives: To evaluate the accuracy of frozen section examination (FSE) for detecting lymph node (LN) metastasis in patients with bladder cancer undergoing radical cystectomy and pelvic LN dissection. To our knowledge, the accuracy of FSE to identify LN metastases in patients with bladder cancer is still undetermined. Methods: The clinical data of 360 patients who had undergone radical cystectomy with pelvic lymphadenectomy for bladder cancer in six urologic institutions were retrospectively analyzed. The nodal regions included were the external iliac, hypogastric, and obturator LNs. The FSE results of the right and left LN regions were compared with the final histopathologic results of the respective LN regions. Results: The final pathologic examination revealed nodal metastases in 65 patients (18.1%). Of the 720 right and left LN regions in 360 patients, 88 (12.2%) were metastatic at the final pathologic examination. Although the FSE findings were negative, the final pathologic examination revealed LN metastases in 26 patients and in 29 pelvic LN regions. All LN regions with positive FSE findings were positive at the final pathologic examination. When we considered the 720 LN regions, the sensitivity, specificity, and positive and negative predictive values for FSE were 67%, 100%, 100%, and 95.6%, respectively. Conclusions: Until innovations in imaging methods improve nodal staging in patients with bladder cancer, performing FSE of the external iliac, hypogastric, and obturator LNs seems to be a reliable procedure for the evaluation of the LNs. The information obtained with FSE of the LNs can be used to determine intraoperatively the extent of LN dissection. © 2007 Elsevier Inc. All rights reserved.