Antibodies to hepatitis B core antigen (anti-HBc) are found in the sera of all individuals infected with hepatitis B virus. A role for these antibodies has been suggested in determining the outcome of infection. In this study, the affinity of anti-HBc antibodies in asymptomatic virus carriers was compared with that of antibodies present in the sera of patients with chronic liver disease. Persistently infected individuals with no evidence of clinical disease were found to have anti-HBc antibodies of greater affinity, compared with the chronic liver disease group. Sera from patients with chronic hepatitis contained high levels of low-affinity antibody whereas antibody levels in asymptomatic carriers were significantly lower. These findings are discussed in relation to the predicted role of anti-HBc antibodies in mediating hepatitis B virus-related hepatocellular injury.