Infection with the hepatitis C virus affects not only the liver but also non-hepatic tissues and may combine with many unrelated diseases and morbid conditions. A number of extrahepatic manifestations have already been recognized. For some of the extrahepatic disorders their association with HCV infection is well established while for others it remains probable or weak. Here, emphasis is given to the well-established extrahepatic manifestations of mixed cryoglobulinaemia, thyroid abnormalities and lichen planus as well as to the newly recognized association with diabetes mellitus, thrombocytopenia and the antiphospholipid syndrome. Pathogenetic mechanisms of extrahepatic and autoimmune features in HCV infection are still unclear and therapeutic decisions in such conditions are difficult. Data on the efficacy and side-effects of therapy with interferon-α and corticosteroids are reviewed and some practical guidelines for treatment are given.