Mullerianosis is a rare entity consisting of an admixture of 2 or more of the following tissues: endometriosis, endocervicosis, and endosalpingiosis. It most commonly affects the urinary bladder and affects females of fertile age. It presents clinically as hematuria, dysuria, and pelvic pain which may be associated with menstruation. Radiologically and macroscopically, it typically presents as a polypoid mass in the dome or posterior wall of the bladder. Histologically, it consists of glands of varying size lined by endometrial, endocervical, or tubal epithelium. Mullerianosis clinically and histologically mimics other benign and malignant lesions. Herein we report a case of mullerianosis of the urinary bladder. This is a rare lesion with less than 20 cases reported in the literature thus far. We believe raising awareness of this poorly recognized entity is of utmost significance in order to avoid misdiagnosis and the following unnecessary radical procedures.