A 48-year-old male patient was admitted with acquired immunodeficiency syndrome (stage III, Centers for Disease Control 1993) and viremic hepatitis B. Blood CD4 count was 15/microliters. Discontinuation of prednisolone, previously prescribed by the patient's family practitioner because of elevated liver enzymes, resulted in severe hepatitis (alanine aminotransferase > 300U/l). Administration of interferon-alpha (9 x 10(6) U s.c. 3 x weekly) was initiated. Serum markers of viral replication disappeared, and aminotransferase levels returned to normal within a few weeks. The patient's serum was found negative for HBsAg after 3 months. Immunohistochemical analysis of liver biopsies before and during interferon therapy showed disappearance of all hepatitis B virus antigens and a marked reduction in inflammatory activity. Hepatitis B virus seroconversion remained stable until the patient died from the syndrome 2 years later. This case shows that in spite of severe HIV-associated immune deficiency with CD4 counts constantly below 100/microliters, interferon-alpha can lead to sustained serological and histological improvement of viremic hepatitis B. Previous administration and discontinuation of cortisone may have helped to reach this effect.