Studies recently suggested that different genetic factors are involved in the development and progression of bladder cancer. In this study, 30 consecutive patients affected by bladder neoplasm were evaluated in order to analyze the frequency of c-erb-2 gene amplification and chromosome 7, 9, 17 aneusomy using fluorescence in situ hybridization (FISH) technique. C-erb-2 gene amplification, chromosome 17 gain and aneusomy were respectively observed in 3.7% (1/27), in 47% (12/27) and in 74% (20/27) of examined tumors. Moreover, chromosome 7 and 9 aneusomy were detected in 74% (20/27) and in 72% (16/27) of specimens. A statistically significant correlation was observed between chromosome 17 aneusomy and tumor stage and grade (r: 0.642, p = 0.0001; r: 0.385, p = 0.04, respectively). In conclusion, we observed a low incidence of C-erb-2 gene amplification, while chromosome 17 aneusomy was confirmed as a marker of advanced and aggressive bladder cancer.