OBJECTIVE To determine the need to standardize the number and location of lymph nodes to be removed during radical cystectomy in patients with invasive bladder carcinoma. METHODS The pelvic lymph nodes from 447 patients (mean age 62.8 years) who underwent radical cystectomy between 1986 and 1997 were evaluated. The number of lymph nodes was correlated with the depth of invasion of the primary tumour (pT), occurrence of nodal metastases, clinical outcome, the operating surgeons and the pathologists dissecting the nodes. RESULTS The clinical follow-up was available for 302 patients (mean follow-up 38.7 months). The mean (range) number of lymph nodes removed was 14.7 (1-46). The number of lymph nodes removed varied significantly among different surgeons but not among pathologists. In pT3 and pT4 tumours, a more extended lymphadenectomy (>/= 16 lymph nodes) correlated with a higher percentage of patients with documented nodal metastases. There was a significant correlation between the number of lymph nodes removed and the tumour-free 5-year survival in patients with pT1, pT2 or pT3 tumours, and in patients with 1-5 positive lymph nodes (P < 0.01). CONCLUSIONS Extensive lymphadenectomy significantly improves the prognosis of patients with invasive bladder cancer and represents a potentially curative procedure in patients with nodal metastases, including micrometastases that may escape detection during routine histopathological evaluation. The results indicate the need for a standardized lymph node dissection.