The concept of chronic hepatitis is very complex. There is no generally recognized definition and no agreement on the nomenclature. In more recent times a subdivision into chronic persisting (CPH) and chronic active (aggressive or progressive) hepatitis (cah) has been proposed. Morphologically CPH has a mononuclear inflammatory infiltration of the portal fields with preservation of the lobules. In positive hepatitis B CPH, orcein-positive milkglass-shaped hepatocytes and washed-out nuclei have recently been established by immunofluorescence. Periportal inflammation (piecemeal necrosis) is characteristic of CAH. Severe forms show hepatocytolysis and confluent necroses in addition. Since there is not always a sharp division between CPH and CAH, an unequivocal diagnosis of clinical, biochemical, serologic and immunological data is required.