We report a rare case of a 45-year-old woman who underwent laparoscopy for a right mesosalpinx mass. Pathologic examination showed a female adnexal tumor of probable Wolffian origin (FATWO). FATWO represents a rare gynecologic tumor and its clinical and pathological features are often ignored. Immunohistochemistry plays the most part in the diagnosis of FATWO. Through this report, we aimed to call attention to this disease in order to better understand the correct treatment and surgical possibilities, and to evaluate and perform the prognosis properly.