Ninety-two British, caucasian, alcoholic patients with liver disese were grouped on the basis of hepatic histology into fatty change, hepatitis with or without cirrhosis, and cirrhosis alone. Men with alcoholic hepatitis with or without cirrhosis showed an increased incidence of the histocompatibility antigen HLA-B8 (P less than 0.02). Increased measles antibody titres were found in patients without cirrhosis with or without hepatitis and were associated with the B8 phenotype in both sexes. Rubella antibody titres and percentage DNA-binding were raised in patients with cirrhosis and showed no association with the B8 phenotype. Concentrations of IgM and IgA were were raised in patients with stetosis and with hepatitis, while in patients with cirrhosis IgG concentrations were also increased. Low titres of autoantibodies were found in all histological groups. It is possible that the development of hepatitis in response to alcohol abuse may be influenced, at least in men, by a gene linked to the B locus. Otherwise, immune processes associated with alcohol-related liver disease are probably secondary phenomena.