Chronic liver diseases may be associated with the appearance of antinuclear antibodies. To further analyze the relationship between connective tissue and liver diseases the sera of 88 patients with chronic liver disorders were examined for the presence of common lupus anti-DNA idiotypes ( 16 6-id, 134-id, and 32 15-id), using an enzyme-linked immunosorbent assay. The 16 6-id was found in 58 (65.9%), the 134-id in 43 (48.9%), and the 32 15-id in 13 (14.8%) of the patients' sera. Distinct diagnostic groups displayed different lupus anti-DNA idiotype profiles. Patients with primary biliary cirrhosis (PBC) and chronic active hepatitis (CAH) had mainly the 16 6 idiotype, while in alcoholic (AC) and in cryptogenic cirrhosis (CC) the 16 6-id and 134-id were the main idiotypes recorded. There was considerable correlation among the different anti-DNA idiotypes but not between any of these idiotypes and an unrelated common anti-HBsAg idiotype. The occurrence of the various idiotypes was not found to be correlated with increased serum immunoglobulin levels. It can be concluded that the similarities between chronic liver diseases and connective tissue diseases are extended also to the presence of specific common anti-DNA antibody idiotypes.