The association of human papillomavirus (HPV) with urinary bladder carcinogenesis is now a controversial issue. In order to certify the presence of HPV DNA in urinary bladder cancers, the polymerase chain reaction (PCR) using five primer sets for detecting various HPV types was used in this study as well as in situ hybridization (ISH) for HPV 16 and 18 detection. In the PCR study of 93 DNA samples extracted from formalin-fixed and paraffin-embedded urinary bladder cancers, no HPV DNA was detected in these tumor samples. The ISH study was also performed on the same tumor samples, but failed to demonstrate any HPV 16- or 18-positive signals in all except one of the tumor samples. However, the PCR failed to demonstrate HPV 16 DNA even in the bladder cancer positive for HPV 16 DNA by the ISH. This ISH technique was able to demonstrate HPV 16 and 18 DNA in eight of 13 paraffin-embedded cervical cancers, in which HPV 16 or 18 DNA had already been detected by the PCR. Our HPV study using PCR and ISH revealed that the HPV status of urinary bladder carcinomas was far different from that of cervical cancers.