Objective To evaluate the diagnostic value of chromosome aberration of urine exfoliated cells by fluorescence in situ hybridization ( FISH ) for patients with bladder carcinoma. Methods Using centromeric probes of chromosomes 3, 7, 17 and region probe of 9p21, we performed FISH on the exfoliative cells in the urinary samples from 30 patients with pathologically confirmed bladder carcinoma and 20 hematuria patients with benign bladder disease controls. Then we noted and analyzed aberrations in the chromosomes. Results The sensitivity and specificity of FISH on detecting bladder cancer were 97% and 100%, respectively. Conclusions It is noninvasive and effective to diagnose bladder cancer with the techique of FISH. It is a rapid, accurate and very sensitive method and can be used in clinical diagnosis.