An enzyme immunoassay (Ortho-HCV ELISA) for antibodies against the hepatitis C virus was used to test serum samples from 39 patients with alcoholic cirrhosis and 34 patients with alcoholic hepatitis or fatty liver. The frequency of a positive result in the cirrhotics was significantly higher than in the alcoholics without cirrhosis (38.5% vs 8.8%, P less than 0.01). However, the positive results in the cirrhotics were associated with high gammaglobulin concentrations, and optical density values in the assay correlated closely with serum globulin (r = 0.73, P less than 0.01). The findings suggest that serum from patients with alcoholic cirrhosis may contain a component that give false-positive results in the assay.