Endometrial adenocarcinomas arising in a complete septate uterus with cervical and vaginal duplication are rare. Here, we report a case of stage III endometrioid endometrial adenocarcinoma arising in a complete septate uterus with a double cervix and vagina coupled with a left serous ovarian cystadenoma in a 35-yearold-female patient. The patient underwent a total abdominal hysterectomy with bilateral salpingooophorectomy and was addressed to the oncologist for adjuvant radio-chemotherapy. We highlight the symptoms, diagnosis, and therapeutic management, and compare them to the recent literature.