A case of leiomyoma of the urinary bladder in a 46-year-old woman is reported. The patient was referred to us because of incidental finding of a mass in the bladder. Cystoscopy revealed a protruding tumor covered with normal-appearing urothelium on the right posterior wall of the bladder. The tumor was well-demarcated from adjacent organs on echography and computed tomographic scan. Transurethral biopsy revealed a bladder leiomyoma. Partial cystectomy was performed. The patient is now apparently free of disease 7 months after the operation.