Testicular tumors in prepubertal boys differ in type and behavior from those seen in adults. Teratomas and yolk sac tumors are the commonest histologic types seen. Teratomas before puberty behave benignly but yolk sac tumors are malignant. The management of yolk sac tumors is in flux and there is little reliable data upon which to base management. A pre-pubertal testicular tumor registry established by the Section on Urology of the American Academy of Pediatrics has provided preliminary data on over 160 boys with testicular tumors, 2/3 of which are yolk sac tumors. Some of this data is included in this overview of prepubertal testicular tumors.