Detection of genetically-changed tumor cells in the urine is one of the new approaches for the screening of bladder carcinomas. In a previous study, numerical aberrations of chromosome 9 were found in 85.18% of bladder tumors studied by the fluorescence in situ hybridization (FISH) technique. The purpose of the present study was to investigate whether chromosome 9 aneusomy alone is a valid, cost effective, biomarker for bladder cancer screening.