Of 32 patients seen in Memorial Center since 1920 with myosarcomas of the bladder or prostate 26 were male and six were female. The tumors arose in the bladder in 20, in the prostate in 11 and in one patient both organs were involved. Sarcomas of the bladder account for two or three of every thousand bladder cancers and for one of every thousand prostate cancers. Seventy-six patients, or approximately 10% of reported cases, have survived 3 years or more from diagnosis. Forty-five of those 76 sarcomas were reported as specific myosarcomas, i.e., embryonal rhabdomyosarcoma, adult rhabdomyosarcoma, leiomyosarcoma or combinations of those three. Thirty-six arose in the bladder, nine arose in the prostate. The most successful methods of treatment have been cystectomy for embryonal rhabdomyosarcoma of the bladder and segmental resection for leiomyosarcoma of the bladder. Rhabdomyosarcoma of the bladder and prostate has seldom been managed successfully, so that no particular treatment can be unconditionally recommended. Embryonal rhabdomyosarcoma of the prostate is as yet an incurable condition.