Summary. Hepatitis C is a major cause of morbidity and mortality in haemophiliacs who received clotting factor concentrates before the availability of virus-inactivated factors in the mid-1980s. Early studies gave conflicting indications as to the severity of hepatitis C (originally termed non-A non-B hepatitis), as mild, slowly progressive hepatitis was documented in several infants and young adults with haemophilia who were examined with repeat liver biopsies, whereas more progressive hepatitis and cirrhosis was documented in others. One major point of dispute was whether these discrepancies could in part be accounted for by epidemiological differences among studies, as hepatitis C acquired early in life may initially run a benign course and later worsen owing to spontaneous recrudescence of hepatitis or interference with such comorbidity factors as alcohol abuse or infection with the human immunodeficiency virus (HIV). In the mid 1990s, the latter infection overshadowed hepatitis C as a cause of death in this patient population. Because hepatocellular carcinoma is emerging as an important complication in haemophiliacs with long-standing hepatitis C virus (HCV) infection who survived HIV infection, and because of recent advances in treating HIV, morbidity and mortality associated with chronic hepatitis C have regained emphasis amongst haemophiliacs. The development of newer interferon-based therapies provides an opportunity for modifying the natural history of HCV infection in a substantial number of haemophilic patients.