Epidemiological evidence is accumulating that sexual history may be associated with prostate cancer, and some studies have suggested a relation between human papilloma virus (HPV) infections and prostate cancer. We measured the presence of antibodies to the major oncogenic HPV types 16, 18, and 33 among 238 subjects with untreated prostate cancer and 210 population-based control subjects. Odds ratios (ORs) were estimated from multivariate logistic regression models, controlling for age and HPV types 16, 18, and 33, simultaneously. HPV types 16 and 18 were not associated with prostate cancer [OR, 0.7; 95% confidence interval (CI), 0.4-1.3 for HPV 16; OR, 0.9; 95% CI, 0.5-1.9 for HPV 18]. There was a possible association between HPV 33 and prostate cancer (OR, 1.6; 95% CI, 1.0-2.7), and there was a significant excess risk for subjects with high antibody levels against HPV 33 (OR when the difference in absorbance exceeded 0.2, 2.3; 95% CI, 1.2-4.1). When HPV antibody levels were modeled as continuous variables, the results were qualitatively similar. The data do not support previous studies that have suggested an association with HPV 16 or 18 and prostate cancer risk. Inconsistent associations with different HPV types seen in different studies suggest that the association may be because of chance, bias, or confounding by some unknown risk factor that may associate with different HPV infections in different populations. Additional studies of the relationship between prostate cancer and other HPV types, notably HPV 33, could be helpful for clarifying the possible role of sexual risk factors.