We investigated the presence of human papillomaviruses (HPVs) types 16 and 18 DNA in formalin-fixed, paraffin-embedded tissues from the urinary bladder (46 transitional carcinomas and 10 non-neoplastic normal urinary samples) to find a possible role for HPV types in urinary tract cancerogenesis. The analysis was performed using polymerase chain reaction followed by filter hybridization with oligonucleotide-specific probes. The HPV16 and/or HPV18 genomes were detected in 23 of 46 (50%) bladder carcinomas and in none of 10 (0%) non-neoplastic urinary samples. These results suggest that HPV16 and 18 may carry a risk for the development of malignancy in the urinary tract as it occurs in the anogenital regions.