Atypical polypoid adenomyoma (APA) is a rare, benign lesion. The tumor occurs in nulliparous women aged 22-48 years (average 33 years) and it has been suggested as being related to prolonged estrogenic stimulation. We describe a case of a 72-year-old woman who presented at our hospital with persistent, worsening urinary incontinence and pelvic pain. Physical examination and pelvic ultrasound disclosed uterine enlargement, a mass in the endometrial cavity and multiple small myomas. Total hysterectomy with bilateral salpingo-oophorectomy was performed. The histological diagnosis for the mass of the endometrial cavity was atypical polypoid adenomyoma. APA should be distinguished from endometrial carcinoma and other malignant uterine neoplasms such as adenofibroma, adenosarcoma and malignant mixed mullerian tumor. The immunohistochemical panel which usually includes alpha smooth muscle actin, desmin, Ki67 and recently CD10 is often helpful in establishing the diagnosis. The treatment may vary depending on the patient’s age, her desire to preserve fertility, and the severity of her symptoms.