Most cases of hepatitis which are due to viral infection or drug injury will resolve promptly. Indeed, in most instances elevated transaminases may be expected to return to normal levels within 3 months. However, in some instances inflammation does not settle but becomes established as a chronic illness. Although the patient may be asymptomatic, the transaminases are intermittently or permanently elevated, liver biopsy shows continuing damage, and there may be evidence of ongoing viral replication. The whole process is associated with a high risk of progression to cirrhosis, chronic liver failure and hepatocellular carcinoma. These then are the parameters which define the entity of chronic hepatitis.