Sexual precocity in a 28-months-old boy and markedly accelerated skeletal growth with large body in a 5 years and 5 months-old-girl are reported. The former resulted from human chorionic gonadotropin-producing hapatoblastoma and the latter from cerebral gigantism associated with hepatoma, These two different disorders are discussed on the common basis of rare association of malignant hepatic tumors with precocious sexual and/or somatic growth. The clinical manifestations, chemical abnormalities, and the radiologic findings are presented with a brief review of the literature.