Following a survey among all Danish haemophiliac patients 49 HIV-negative patients with chronic hepatitis C were offered enrollment in a randomized controlled open label study comparing two different maintenance regimens following standard interferon-alpha-2b treatment. Dose modifications and treatment discontinuation were based upon changes in transaminase levels. Forty-seven patients enrolled received 3 MU of alpha interferon thrice weekly (TIW) for 3 months. Twenty-six nonresponders had their dose increased to 6 MU TIW for an additional 3 months, while 21 responding patients continued on 3 MU TIW. At 6 months, 25 patients with a complete or a partial biochemical response were randomly allocated to either a fixed dose regimen (13 patients) (3 or 6 MU thrice weekly) or an individualized dose regimen (12 patients) tapering interferon dose from 3 or 6 MU by one-third every 2 months if transaminases were persistently normal. The remaining 22 biochemical nonresponders were followed for an additional 6 months without further treatment. After 12 months of treatment, 18 patients (38%) had a virological response, irrespective of regimen, and seven patients (16%) had a sustained virological and biochemical response after 6 months of follow up. Overall, the individualized treatment regimen did not seem to offer any advantage over the fixed dose regimen. The response to alpha interferon treatment in Danish haemophiliac patients with chronic hepatitis C immediately after treatment is comparable to that obtained in previous studies among nonhaemophiliacs. However, a sustained virological and biochemical response was seen in only 16% of treatment patients.