Germ cell tumors are rare in childhood. They are localized - in decreasing frequency - in the sacrococcygeal area, in the ovary, in the mediastinum, in the testis and elsewhere. Seminoma, dysgerminoma, teratoma and yolk sac tumors are "real" germ cell tumors. As to classification of germ cell tumors of all localizations the (modified) schemes of Pugh and Cameron (1976) and of the WHO (Mostofi) and Sobin, 1977) are suitable. The tumors should be classified according to both systems. Morphology and biological behaviour including prognosis of the germ cell tumors depend heavily upon patient's age at diagnosis and tumor localization. 92 germ cell tumors were already examined and analyzed in the childhood tumor registry, comprising (due to selection) 55 malignant tumors (17 of the ovary, 16 of the testis). In the testes of children yolk sac tumors and differentiated teratomas are seen most frequently with maximum age peak in infancy and early childhood. Starting in or after puberty malignant teratomas of the testis do occur. Paratesticular tumors (especially rhabdomyosarcomas) are more common (in relative and absolute numbers) in childhood as compared to adults.