To study the role of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in patients with primary biliary cirrhosis (PBC) against the background of HBV and HCV infection in the general population, serum specimens from a consecutive series of 27 patients with PBC and 108 age/sex matched 'healthy subjects' as control group were submitted to assays for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), antibody to hepatitis B surface antigen (anti-HBs) and antibodies to hepatitis C virus (anti-HCV). None of the patients with PBC were HBsAg or anti-HCV positive while 17 (15.7%) and 6 (5.6%) of 'healthy' controls were HBsAg positive and anti-HCV positive (P = 0.017 and 0.26). Patients with PBC also had a significantly lower prevalence of HBV infection than matched controls (70.4% vs 88.9%, P = 0.022). The results suggest that neither HBV nor HCV plays any significant role in the pathogenesis of PBC, and that PBC would not develop or be masked in patients with HBV or HCV infection.