Malignant ovarian tumors only account for 3 per cent of all malignancies under 15 years of age, and more than two third of them are of germ cell origin. Abdominal mass and/or pains are the usual revealing symptoms and abnormal sexual prematurity is infrequently encountered. Diagnostic ultrasonography is currently the most useful imaging investigation. Alpha-foeto-protein (alpha-FP) serum determination is mandatory before surgery to indicate the presence of endodermal sinus tumor cells. Surgical procedure is in childhood usually restricted to unilateral salpingo-oophorectomy, if allowed by tumoral spreading which is carefully searched in the abdominal cavity. Thus will be defined, along with the post-operative lymphangiography, the extension of the tumor, according to the staging system of Wollner (Memorial Hospital NY) more than the FIGO. Malignant teratomas are the most frequent malignant germ cell ovarian tumors in young females. They may realize pure or mixed pathological types of immature teratoma, embryonal carcinoma, endodermal sinus tumor and very seldom choriocarcinoma. Serial assays of serum alpha-FP are of utmost value to follow therapeutic progress or detect recurrences. Since new sequential multidrug protocol including, vincristine, actinomycin D, cyclophosphamide, adriamycin, méthotrexate and cis-platinum, protracted survivals are to be expected in a higher number of patients with localized stages and even in some with advanced disease. Value of extended pelvi-abdominal and/or lymph node radiotherapy is still under evaluation. Ovarian dysgerminomas are radiosensitive tumors in which chemotherapy is as a rule not indicated. Relapses may be most often prevented by a prophylactic irradiation of iliac ipsilateral, lumboaortic, mediastinal and supraclavicular nodes. Among functional ovarian tumors, mainly granulosa cell types with isosexual precocity, malignant tumors are so rarely encountered that no complementary treatment has to be performed after a complete resection. Cystadenocarcinoma or borderline ovarian epithelial tumors occur after puberty and require the same treatment as in adult though keeping a conservative view. Ovarian deposits of Burkitt's tumor may account in some exposed african areas for most ovarians malignancies in childhood. Gonadoblastomas with both stromal and germ cell elements are exclusively to be found in dysgenetic gonads.