Acute liver failure (ALF) is an uncommon but dramatic clinical syndrome characterized by rapid loss of hepatocyte function in an individual without pre-existing liver disease. The syndrome is rare in the United States, with an estimated incidence of 2000 cases each year.1 Acute liver failure should be suspected in any patient with new-onset liver disease associated with an increase of prothrombin time. A frequently used definition of ALF is the development of encephalopathy within a short interval after the initial onset of liver disease.