Liver transplantation (OLTx) has become a common life-saving procedure for individuals with chronic advanced liver disease. It is also used in the clinical treatment of patients with fulminant hepatic failure and those with primary neoplastic disease of the liver. Despite its overall success in restoring meaningful life to those who undergo the procedure, the posttransplant life of a liver allograft recipient is not without hazard. A common problem following liver transplantation is the finding of abnormal liver injury tests reflecting a "hepatitis" that can not be ascribed to allograft rejection. The majority of such cases are a consequence of either a technically flawed operation, drug-induced liver injury, or one or another form of viral hepatitis. Each of these problems is discussed in the following clinical review.