We investigated the prevalence of anti-HCV in 160 consecutive patients with primary biliary cirrhosis. By ELISA, 19 (12%) were positive, as compared to a 68% prevalence in 135 patients with chronic non-A, non-B hepatitis. Serum IgG levels were significantly higher in the anti-HCV positive group. By RIBA, seropositivity was confirmed for 4 patients, whereas 7 were indeterminate. A slight, non-significant reduction of life expectancy was found in anti-HCV positive patients. Until reliable and independent confirmatory tests become available, definitive conclusions on the importance of anti-HCV positivity in primary biliary cirrhosis are improper.