Sarcoma of the urinary bladder is an uncommon neoplasm, and leiomyosarcoma is even more uncommon. In a careful review of the literature we were able to find records of only 13 cases of leiomyosarcoma. The case to be reported here brings the total up to 14. It is possible that this list is not complete and that some cases may have been overlooked. Three cases, 1 reported by Albarran (1881) and 2 by Targett (1896), were referred to by Rabson; but, as he suggested, the evidence is insufficient for a positive diagnosis and hence they are not included in the present tabulation. Before discussing this subject in detail, we should like to report the following case. REPORT OF A CASE N. M., a man aged 55, single, was first admitted to the Presbyterian Hospital on Jan. 5, 1936. The patient had had three attacks of gonorrhea, one of which was