We retrospectively investigated anti-HCV prevalence in a series of 160 consecutive patients with primary biliary cirrhosis who presented between 1980 and 1989. Of these, 19 (12%) were positive for anti-HCV by C-100 ELISA. Serum IgG levels were significantly higher in anti-HCV-positive patients and correlated to optical density values. A serum sample was again collected from all the patients from the same series who were seen in 1990 for follow-up, after a median period of 32 months. Anti-HCV positivity was found to be substantially unchanged in this subgroup of patients when the freshly drawn blood samples were retested with C-100 ELISA, while it increased from 10% to 17% when second generation ELISA was used. Three of the C-100 ELISA positive samples were C-100 RIBA reactive, and six of the second generation ELISA positive samples were 4-RIBA reactive. The HCV genome was not detected in any of the seven anti-HCV C-100 ELISA and second generation ELISA positive sera which were studied by polymerase chain reaction, including four cases confirmed by 4-RIBA. Life expectancy, as determined by survival analysis, did not differ significantly between anti-HCV-positive and -negative patients. These findings suggest that anti-HCV positivity does not influence the clinical presentation and course of primary biliary cirrhosis.