Background: Paratubal masses are common, but paratubal carcinoma is  an extremely rare entity. Case: We report a case of a 44-year-old nulliparous female who suffered from abdominal pain for three months. Abdominal and pelvic ultrasound revealed a 30 cm left adnexal mass originally. Laparotomy with bilateral salpingo-oophorectomy was performed. Final pathology indicated a heterogeneous tumor with benign, borderline, and endometrioid carcinoma areas. A repeat surgery was decided in order to complete hysterectomy, omentectomy, pelvic and paraaortic lymphadenectomy. Surgical staging did not reveal residual disease at pathological examination. After 36 months of follow-up, no recurrence has occurred. Conclusion: To our knowledge, no case of paratubal invasive endometrioid adenocarcinoma has previously been described. This case has been managed according to the recommendations of ovarian cancer, which seems to be an acceptable option.