The aim of the present research was to investigate human papillomavirus (HPV) infection by means of immunohistochemistry and in situ hybridization in 76 bladder cancer specimens. A biotinylated DNA probe that recognizes HPV 6/11, HPV 16/18 and HPV 31/33/35 was used for in situ hybridization. A polyclonal antibody recognizing HPV capsid antigen (HPVcAg) was used for immunohistochemistry. In situ hybridization and immunohistochemistry were developed by alkaline phosphatase and immunogold-silver techniques respectively. Our results showed that 25 (32.8%) out of 76 bladder carcinoma specimens reacted with HPVcAg. Twelve (15.7%) out of 76 cases were positive for HPV 16/18-DNA using non-isotopic in situ hybridization. Sixteen cases had koilocytosis. No positive signals were found for HPV 6/11 or 31/33/35-DNA probes.