Acute viral hepatitis has several identifiable morphologic components but the major categories are (1) cytopathic, (2) inflammatory, and (3) regenerative. Each category has independently variable characteristics. Extreme alterations related to severity of disease, alteration of immune response, or pre-existing liver disease may result in diagnostic difficulties for the pathologist. In contrast to the usual concept, patients who survive fulminant viral hepatitis rarely, if ever, develop cirrhosis and those who have severe hepatic necrosis from hepatitis also do not usually develop serious sequelae of that disease except in the older age group where the difficulty is in impaired regeneration (IR). The usual criteria for the diagnosis of chronic active hepatitis or chronic aggressive hepatitis need a thorough review since many of the variations of acute viral hepatitis result in histologic patterns that might be considered to be chronic aggressive hepatitis using the previous definitions; yet such patients recover without developing chronic liver disease. Chronic active hepatitis, a progressive hepatic disorder, is characterized by changes in the distribution of necrosis and regeneration within the lobule from that usually observed in acute viral hepatitis. Persistent viral hepatitis, a development in 10 to 12 per cent of adult patients after icteric acute disease, is characterized by a "cobblestone" hepatocellular change that resembles continued regeneration, focal hepatocytolysis, and often portal lymphoid hyperplasia. Apparently with time, these histologic features fade and the incidence, in type B PVH, of "ground glass" HBs Ag laden cells increases. This may reflect a continued adaptation of host and virus to one another.