The hepatitis B virus (HBV) status of six unselected South African Black children, aged 10 to 16 years, with hepatocellular carcinoma (HCC) was investigated. The characteristics of the tumor were similar to those seen in Black adults. Hepatitis B surface antigen and antibody to the core antigen were present in the serum of all the children, and hepatitis Be antigen was detected in four of the children. The serum of the two patients without e antigen was positive for e antibody, and all sera were negative for hepatitis B surface antibody. Taken in conjunction with the HBV status of southern African Black adults with HCC, these findings raise the possibility that nearly all, if not all, Black patients with this tumor are or have been infected with HBV. Moreover, if HBV is oncogenic, tumor formation may occur within 10 years of the initial infection, which occurs in early childhood in southern African Blacks.