Chronic hepatitis (CH) may be defined as persistence of an inflammatory reaction in the liver for > 4 months. Different immune mechanisms of liver damage are operative in children with the three common types of CH. In autoimmune CH the cytotoxic effect is mostly confined to the non-T cell lymphocyte fraction. Autoimmune CH is steroid responsive and has a generally favorable prognosis. In hepatitis B virus (HBV) hepatitis both T and non-T lymphocytes are responsible for the cytotoxic reaction. Steroid or interferon treatment is controversial and the prognosis is less favorable. Hepatitis delta virus (HDV) hepatitis only occurs in children with HBV hepatitis as either a co-infection or superinfection. As a co-infection the HBV is usually eliminated and CH does not ensue. Superinfection with HDV, however, frequently leads to rapidly progressive liver damage and a more serious prognosis. Non-A, non-B (NANB) hepatitis is a diagnosis of exclusion. In NANB hepatitis, the cytotoxic effect is predominantly T cell. NANB hepatitis generally runs a mild course, and no treatment is usually recommended.