Fulminant hepatic failure is caused by a variety of viruses, toxins, and metabolic derangements. The hepatitis C virus (HCV) causes indolent development of cirrhosis and has not been associated with fulminant hepatic failure. We report the first documented case of fulminant hepatitis C in the United States. The patient developed jaundice and stage IV encephalopathy. Initial laboratory evaluation did not reveal the etiology. The patient survived without liver transplantation. Three wk later he was found to have a positive HCV RNA and anti-HCV antibody seroconversion. He continued to improve with alpha-interferon treatment and has normal liver function and a negative HCV RNA 15 months later.