Female adnexal tumors of probable Wolffian origin are rare. Although the histological features of the benign tumors are recognized, features of malignancy are not well defined in published work because these tumors are particularly rare. In this study, we report an 81-year-old woman presenting with a 6-month history of postmenopausal bleeding. A pelvic transvaginal ultrasound scan demonstrated a midline, highly vascular, predominantly solid pelvic mass, approximately 14 cm, posterior to the uterus. CA-125 was moderately raised. She underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy and infracolic omentectomy. Immunohistochemical staining and electron microscopy supported the diagnosis of female adnexal tumor of probable Wolffian origin. There was significant and widespread nuclear pleomorphism with increased mitotic activity endorsing the diagnosis of a malignant tumor. Seven months after initial surgery, follow-up magnetic resonance imaging showed a mass with a maximum diameter of 7 cm in the region of the right adnexa consistent with a recurrence. The patient declined further treatment.