AbstractThe overall prevalence of anti‐HCV antibody in a group of 125 haemophiliacs was 62%. Four patients who had never received replacement therapy were anti‐HCV negative. Of the 121 patients injected regularly with commercial concentrates, 76 were already anti‐HCV seropositive in 1985 and remained so throughout the follow‐up. Two patients seroconverted in 1987 without obvious signs or symptoms of hepatitis. Our patients were treated with dry heat‐treated concentrates since 1985 and with wet heat‐ or solvent/detergent‐treated concentrates since 1988. The absence of further seroconversions and of symptoms of acute post‐transfusion non‐A, non‐B hepatitis since 1988 suggest that present virucidal treatments of concentrates are effective in preventing HCV transmission. Anti‐HCV positivity appeared to be unrelated to the type and degree of haemophilia as well as to the presence of antibodies to hepatitis B virus, human immunodeficiency virus type 1, and hum