This pilot study was designed to establish the effect of long term alpha interferon treatment in haemophilia patients with chronic hepatitis C. Overall, three of eight (37.5%) patients showed a complete response, three of eight (37.5%) a transient response, and two of eight (25.0%) no response. HCV-RNA detection by polymerase chain reaction was more sensitive in detecting relapse than alanine amino-transferase (ALT) activity measurement, suggesting that current interferon schedules based on the ALT response should be re-evaluated critically.