Yolk sac tumor, so called endodermal sinus tumor, is a rare and highly malignant germ cell tumor. Nine patients with histopathological diagnosis of yolk sac tumor have been followed in the Pediatric Oncology-Hematology Research Center. The Patients’ ages ranged from 1.5 to 9 years. Six were female, three were male. While in seven of the patients yolk sac tumors occurred in gonads (three ovarian, four testicular), in the other two they were localized in extragonadal sites which were sacrococcygeal regions. Treatment approaches have ranged from partial surgery to radical excision according to the stage of the tumor, combined chemotherapy and radiotherapy. Five patients received triple chemotherapy, VAC (Vincristine, Cyclophosphamide and Actinomycin-D) while two patients were given a more intensive regimen (Actinomycin D, Cyclophosphamide, Vincristine, Adriamycine, Bleomycine and Cisplatinum). Only one patient received complementary radiotherapy at the dose of 40 Gy. to the sacrococcygeal region. Three patients died, and four of the others have been in complete remission with a mean follow-up of sixty-three months. Long survivors were the two patients whose tumors were completely removed prior to chemotherapy.