Ovarian yolk sac tumor (YST) is a malignant ovarian neoplasm differentiated from primordial germ cells that occur in young age, while endometrioid carcinoma (ECA) is a müllerian epithelial tumor that usually occurs in older patients. The coexistence of an ovarian ECA and YST component is very rare. Only 12 cases have been reported until now according to a Medline search of the English literatures. We present a case of a simultaneous ECA and a YST component in a 35-year-old woman. Exploratory laparotomy was performed. The parts of both ovaries that showed an endometrioid-like glandular pattern were positive for cytokeratin 7 and negative for AFP, but the YST component was negative for cytokeratin 7 and positive for AFP. After completion of four courses of BEP chemotherapy, two courses of taxane and carboplatin chemotherapy were added. The patient failed to respond and succumbed to the disease after 12 months of follow-up.