Urinary basic fibroblast growth factor (bFGF) was determined by a competitive sandwich ELISA test in 26 patients with transitional bladder cancer and 26 normal volunteers or subjects with benign urological diseases. The median bFGF value in the patient group was 3.41 ng bFGF/g creatinine (range: 0-153.6), significantly higher than the median levels in the control group (1.39 ng/g creatinine; range: 0-4.5). On the basis of the optimal cut-off point of 2.64 ng bFGF/g creatinine, the sensitivity of the test for detecting bladder cancer was 61.5% and the specificity 76.9%. We also studied 17 individuals successfully treated for a previous bladder cancer and with no evidence of disease at the moment of urine collection (NED group). These subjects showed similar urinary bFGF levels as those observed in the control group (median 0.24 ng bFGF/g creatinine, range 0-5.1). Our data suggest that the dosage of urinary bFGF could be a non-invasive useful assay in the management of bladder cancer patients.