The critical factors and etiological role of human papillomavirus (HPV) infection in the development of female bladder tumor were examined. Eighty-four female patients with primary bladder tumor were studied. After DNA extraction from each paraffin-embedded tissue, HPV-DNA and genotype were checked. In cases of all HPV-positive cases and some HPV-negative cases, in situ hybridization (ISH) for high-risk HPV-DNA, and immunohistochemical analysis for p16-INK4a were performed. HPV-DNA was detected in 5 (6.0%) of 84 eligible patients, and HPV16 was detected in 3 patients, and HPV6 and HPV52 was detected in one case, respectively. HPV-DNA was detected frequently in younger patients and in patients with a history of cervical cancer. In four high-risk HPV-positive cases, high-risk HPV-DNA was present in tumor tissues, and p16-INK4a was expressed moderately or strongly. Two cases had a past history of cervical cancer. In these 2 cases, the same HPV type (HPV16) was detected from bladder tumor and cervical cancer. High-risk HPV-DNA ISH signals and p16-INK4A expression were also detected widely in these cervical cancer tissues. HPV infection is likely to play an important role in the development of female bladder tumor at younger cases with a past history of cervical cancer.