Endometriosis in the urinary tract is rare and, if present, it often involves the urinary bladder. Vesical endometriosis is usually manifested with periodic hematuria, micturition pain and urgency- frequency associated with menses. Herein two cases are presented as isolated vesical endometrioma involving detrussor muscles; neither exhibited classical symptoms and both were identified via ultrasonography as a broad-base mass protruding into the bladder lumen and contiguous to the uterine body. Partial cystectomy was performed and the patients recovered well. Cystoscopy follow-up three months later showed no evidence of recurrence or residual tumor.