Human papillomavirus (HPV) detection was done using the polymerase chain reaction technique on tumor tissue from 44 patients with transitional cell carcinoma of the urinary bladder. Only one of the 44 was associated with HPV infection. The HPV-positive patient was not known to have immunodeficiency or genital warts, and the tumor was not morphologically different from the other tumors. Control experiments excluded the possibility that this finding was caused by contamination of the sample. This study confirms that HPV infection is a. rare condition in bladder carcinoma.