The age distribution of testicular cancer is bimodal with a large peak in young adulthood and a smaller peak in early childhood. Tumors occurring in adolescence have a similar histological pattern and natural history to those occurring in older adults. However, prepubertal testis tumors occur with distinct histologic patterns and a natural history that differs from that of adult tumors (Table 23.1). Not surprisingly, the management of prepubertal tumors differs as well. The incidence of testis tumors in children is 0.5–2.0 per 100,000 children accounting for 1–2% of all pediatric tumors (Coppes et al. 1994). Yolk sac tumors account for the overwhelming majority of malignant prepubertal testis tumors. The appropriate management of prepubertal yolk sac tumors has been clarified by recent multicenter trials (Haas et al. 1999; Rogers et al. 2004; Cushing et al. 2004; Mann et al. 2000; Lo Curto et al. 2003; Schlatter et al. 2003). Much rarer malignancies in children include some stromal tumors and dysgerminomas occurring in association with gonadoblastoma in dysgenetic gonads. However, unlike in adults, the majority of tumors in children are actually benign, with teratomas being the most common (Pohl et al. 2004). This has important implications for the initial management of testis tumors in children.