Endodermal sinus tumor, also known as yolk sac tumor (YST), is a malignant germ cell tumor that most frequently occurs in the testis, the ovary, and sacrococcygeal areas in children. YSTs are highly aggressive and because of the early metastatic or invasive pattern, their prognosis has been poor. Treatment methods for YSTs are usually intensive, including multiagent chemotherapy, and have shown to improve patient survival significantly; therefore, it is important to consider the reproductive function of these patients with long-term survival. Herein, we present the case of a 31-year-old female, who was diagnosed with unilateral ovarian YST at the age of 13. The patient was treated with fertility-sparing surgery and postoperative adjuvant chemotherapy. During the subsequent long-term follow-up, she was not only free of disease, but also had a successful, naturally conceived pregnancy at 31 years of age. We, therefore, conclude that YST is a curable disease, and that fertility-preservation surgery and subsequent immediate combination chemotherapy is the treatment of choice.