Prostatic carcinoma is the leading second cause of cancer in men. Previous epidermiological studies implicated human papillomavirus as an infectious agent. Since there are only limited studies on the association of HPV to prosate cancer, we examined the prevalence of HPV infections in korean prostate cancer patients. We observed that out of 26 cases, 4 cases and 5 cases were infected by HPV 16(27%) and HPV 18 (31%), respectively and 3 cases by both (46%) and at least 18 were positive for HPV (69%). For these samples, immunohistochemical detection of the p53 and proliferative cell nuclear antigen (PCNA) were also studied, using monoclonal antibodies. Sixteen of 26 (61%) showed immunostaining for p53 protein. While 8 samples with no HPV infection (100%) showed all positive for p53 protein staining, less than half of the 18 patients with any HPV infection (44%) showed p53 protein staining. These findings indicate that altered expression of p53 protein occurs in the more than half of prostate cancers, however, p53 expression is less frequent in HPV infected tissues. This implies that there might be an inverse correlation in general between HPV infection and p53 amplification. However, while 50% (4 of 8) of HPV negative prostate cancer was positive for PCNA staining, 13 out of 18 HPV infected patients (72%) were positive. Therefore HPV infection is more strongly associated with increase proliferation. In addition HPV infected cancer patients are generally in more advanced status implying that HPV infection plays a role in the development of highly malignant prostatic carcinomas, eventhough the statistical significance of this interpretation might be waited for the analysis of more cases.