The epidemiology of primary hepatic malignancies in U.S. children is poorly characterized. We analyzed the incidence, mortality, and characteristics of primary hepatic malignancies in U.S. residents less than 20 years of age. Fatal primary hepatic malignancies in persons less than 20 years of age, between 1979 and 1996, were identified using the multiple-cause-of-death database (National Center for Health Statistics). Histologically confirmed primary hepatic malignancies occurring between 1973 and 1997 were identified using the Surveillance, Epidemiology, and End Results (SEER) database. Between 1979 and 1996, 918 primary hepatic malignancy deaths (average, 0.7/1,000,000/year) were reported nationally among persons less than 20 years of age; rates were higher among Asians and among foreign-born children. Between 1973 and 1997, 271 primary hepatic malignancy cases were reported to SEER among persons less than 20 years of age, of which 184 (67%) and 83 (31%) were hepatoblastoma and hepatocellular carcinoma, respectively. Among children less than 5 years of age, hepatoblastoma accounted for 91% of primary hepatic malignancy cases, whereas among those 15 to 19 years of age, hepatocellular carcinoma accounted for 87% of cases. Five-year survival for hepatoblastoma was 52%, compared with 18% for hepatocellular carcinoma. In the SEER sites, between 1973 and 1977 and 1993 and 1997, hepatoblastoma rates increased (0.6 to 1.2/1,000,000, respectively), while hepatocellular carcinoma rates decreased (0.45 to 0.29/1,000,000, respectively). In conclusion, histologically confirmed hepatocellular carcinoma was reported in children less than 5 years of age, also, where hepatoblastoma is the predominant primary hepatic malignancy. Hepatocellular carcinoma has worse survival rates than hepatoblastoma, and its incidence has not increased. Better maintenance of databases may provide information about associated factors behind this unexpected occurrence.