Our findings clearly show the prognostic potential of in situ hybridization-based determination of Chr 17 polysomy and HER2 amplification in bladder cancer, while the detection of HER2 and p53 protein expression by immunohistochemistry can neither approximate the prognostic stratification results of the genetic-based method nor further increase its accuracy. The gene discussed is ERBB2; the disease is urinary bladder cancer.