The term "chronic hepatitis" includes diseases of different etiology, i.e. viral (hepatitis B virus, non-A/non-B hepatitis virus[es]), drug-induced (e.g. oxyphenisatin, alpha-methyldopa), metabolic (Wilson's disease, alpha 1-antitrypsin deficiency) and so-called "autoimmune" hepatitis. In the clinical course, hepatitis running for up to 3 months is considered acute; when lasting for 3-6 months it is termed prolonged, and chronic hepatitis means a duration of more than 6 months by definition. In chronic hepatitis there is international agreement on basing nomenclature on morphologic findings and on distinguishing chronic persistent hepatitis (with a predominantly lymphocytic inflammation restricted to portal tracts) from chronic aggressive (or active) hepatitis. The latter is typified by piecemeal necrosis in the periportal areas (activity a); additional piecemeal necrosis along fibrous septa or bridging hepatic necorsis is the key feature for activity b. In hepatitis B virus infection, the symptomfree carrier of the virus with no inflammation in biopsy, or merely nonspecific reactive hepatitis, must be included under the heading of chronic hepatitis. Cirrhosis, however, although resulting from necrosis, inflammation and fiber formation, refers exclusively to the disturbance of lobular architecture and its microcirculatory consequences. The term "cirrhosis" is thus not included in the definition of chrome hepatitis and should be evaluated separately as an entity in its own right.