Severe chronic active hepatitis, defined as the presence of a fivefold increase in serum aminotransferases and a twofold rise in gamma globulin for at least 10 weeks, is considered a progressive immunological liver disease requiring corticosteroid treatment, particularly when serum autoantibodies and a severe lymphoplasmacellular periportal infiltrate are found in the liver biopsy specimen. A 38 year old man who fulfilled the criteria for severe chronic active hepatitis is described. His sex, his homosexuality, and the presence of antibodies against HIV, however, led to the suspicion of a coinfection with hepatitis C virus (HCV) rather than autoimmune disease. The rapid and complete response to alpha interferon treatment and a recently available positive antibody test for HCV supported this view. These findings indicate that a HCV related chronic active hepatitis can present as the severe autoimmune type of chronic active hepatitis. Moreover, as in HBV infection, the response to treatment differs from that of autoimmune severe chronic active hepatitis.