Endometrial carcinoma with a germ cell tumor component is a rare event. Here we report a uterine neoplasm with a unique combination of endometrioid adenocarcinoma and mixed germ cell malignant elements. A 28-year-old woman with abnormal vaginal bleeding, an abdominal mass, and elevated alfa-fetoprotein and beta-human chorionic gonadotropin (β-hCG) levels had a history of biopsy of an omental mass and chemotherapy in another hospital one month before her referral to our department. Histologic examination of the mass removed from the omentum revealed an endometrioid adenocarcinoma with yolk sac tumor-like differentiation. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, infracolic omentectomy, and removal of metastatic disease were then undertaken at our hospital. Postoperative chemotherapy was given. Eight months postoperatively, serum alfa-fetoprotein and β-hCG rose again. Cases with primary yolk sac tumors of the endometrium or endometrial carcinoma with trophoblastic differentiation in the literature were reviewed.