The aim of this chapter is to provide appropriate detail about germ cell tumor of ovary. The germ cell tumors of ovary are histologically different heterogeneous group of tumors that are derived from the primitive germ cells. They represent 30% of all ovarian neoplasms. About 95% germ cell tumors are benign cystic teratoma. Malignant germ cell tumors consist of only 3% of all ovarian malignancies. Majority of the malignant germ cell tumors are seen in children and young women. Dysgerminoma, yolk sac tumors, embryonal carcinoma, polyembryoma, choriocarcinoma, teratomas and mixed germ cell are different types of germ cell tumors of ovary, which are discussed in this chapter. Clinical features, histopathology, prognosis and treatment of dysgerminoma, yolk sac tumors, embryonal carcinoma, polyembryoma, choriocarcinoma, teratomas and mixed germ cell are discussed in throughout the chapter. 44 well-colored figures are also presented in this chapter.