Serum antibodies to double-stranded 'native' DNA have been measured in acute and chronic liver diseases using the Farr technique. Elevated levels of DNA binding were found in all groups of patients, with the highest levels in acute viral hepatitis and lowest in primary biliary cirrhosis. All patients with hepatitis B surface antigen-positive chronic active hepatitis had elevated levels, hence persistent elevation of DNA binding after acute type B hepatitis might be an unfavourable prognostic marker indicating progression to chronic active hepatitis, DNA antibody levels will not offer diagnostic help in liver diseases, or help to follow the response of patients with 'lupoid' hepatitis to corticosteroid therapy. Production of DNA antibody may be a response to release of DNA from damaged hepatocytes.