Antibody to hepatitis C has been variously detected in 1-20% of haemodialysis patients in recent studies from overseas. To determine the frequency of antibodies to the C100-3 protein of the hepatitis C virus (anti-HCV) a cross-sectional study was performed in 60 patients on maintenance haemodialysis in Western Sydney. Six patients (10%) were anti-HCV seropositive. Four of the six anti-HCV positive patients were also hepatitis B core antibody positive, compared with nine of 54 anti-HCV negative patients (p less than 0.05). All anti-HCV positive patients had received multiple blood transfusions. Serum alanine aminotransferase (ALT) was not useful as a screening test. Recent evidence suggests that anti-HCV seropositivity underestimates infectivity.