Acute hepatitis B is a self limiting disease that resolves spontaneously in 95% of patients who acquire the infection in adulthood. Patients with acute hepatitis B, however, usually take between four and 12 weeks to recover; the personal, social, and sanitary costs associated with this are high. Also, 5-10% of patients with acute hepatitis B go on to develop chronic liver disease. Hepatitis C, by comparison, is an asymptomatic disease associated with a high progression to the chronic stage. At least 50% ofpatients with post-transfusion hepatitis C develop chronic liver disease or cirrhosis. While the efficacy of alpha interferon in chronic hepatitis B and C is now well established, only preliminary evidence for use in the acute phase exists. This paper reviews the preliminary evidence and concludes that, given the high risk of progression to the chronic stage, the use of interferon in acute hepatitis C should be recommended.