Endodermal sinus tumor of the ovary can be differentiated histologically and immunohistochemically from ovarian embryonal cell carcinoma. A case report of a patient with endodermal sinus tumor is presented in which a long-term remission was achieved by unilateral adnexectomy and combination chemotherapy. Review of the current literature indicates that tumor removal followed by combination chemotherapy with vincristine, actinomycin D, and cyclophosphamide is the most effective method of therapy for this highly malignant ovarian neoplasm. The addition of hysterectomy with contralateral ovariectomy or radiation therapy does not appear to significantly improve the survival of patients with this tumor. Serial plasma determinations of alpha fetoprotein provide biochemical monitoring of response to therapy and may be useful in predicting occult tumor recurrence.