We describe the case of a 62-year-old man with chronic irritation of the urinary bladder resulting in dysuria and hypogastric pain. Three neoplasms measuring 0.5, 1, and 1.5 cm, respectively, were observed by cystoscopy and removed by transurethral resection (TUR). Histologic examination showed a complex folding of squamous hyperplastic epithelium around a connective tissue core. The superficial epithelium contained numerous koilocytes. The double polymerase chain reaction (PCR) detected DNA of type 11 human papillomavirus (HPV). The diagnosis was condyloma acuminatum of bladder. Three months later the patient presented with fever, and a new cytoscopy demonstrated an ulcerated, exophytic 4.5 cm mass. Histopathology showed a squamous carcinoma with papillomatous structure, pronounced viral koilocytosis, and irregular invasive deep margin. HPV type 11 was found with double PCR. The diagnosis was warty carcinoma arising in condyloma acuminatum. To the best of our knowledge, this is the first case of warty carcinoma of the urinary bladder described in the literature. We discuss the relationship between the infection by HPV and the development of condyloma acuminatum, its evolution toward a well-differentiated squamous carcinoma, and its distinction from verrucous carcinoma. Int J Surg Pathol 8(3):253-259, 2000