The incidence of testicular cancer in white adults in the United States increased during most of the last half of the 20th century, but information on trends in the occurrence of prepubertal testicular cancer is lacking. We analyzed a population-based cohort to determine whether the incidence trends of prepubertal testicular germ cell tumors have risen similarly to those seen in adult testicular tumors.We identified cases of histologically confirmed germ cell testicular cancer in boys aged 0 to 14 years, of all races, from 1973 to 2000, through the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. The variables analyzed included age, race, tumor histologic type, and year of diagnosis.A total of 131 cases of testicular germ cell cancer were diagnosed among boys of all races, with an overall incidence of 1.6 cases per 1 million person-years. Yolk sac tumor was the most common, followed by teratoma. Choriocarcinoma and seminoma were equally rare. Tumors were most common among whites during early infancy. No secular trends in incidence rates were identified.Prepubertal testicular cancer is rare. All tumors were more common in whites. In contrast to adult testicular cancer, no clear trend over time was found for prepubertal tumors. Whatever the reasons for the increased incidence of testicular cancer over time in men, they do not seem to bear on the risk of testicular cancer in boys.