We present a rare case of carcinosarcoma of the prostate occurring in a 60-year-old white male. This diagnosis was initially missed after a transurethral resection of the prostate (TURP) had been performed to alleviate the patient's urinary obstructive symptoms. After recurrence of symptoms within a short period, another TURP was performed and the diagnosis of carcinosarcoma was then established. The patient then underwent a radical cystourethroprostatectomy with bilateral lymphadenectomy and ileal conduit diversion. Carcinosarcoma of the prostate is a very aggressive disease that often has a poor prognosis, especially when it has spread out of the prostate. Surgical removal of the prostate seems to be the best option for treatment in the select group of patients in which the disease remains confined to the prostate.