Twenty-three HIV/hepatitis C virus (HCV)-co-infected patients received dose-escalated IFN-alpha (5 MIU/day) induction therapy for 10 weeks, followed by 36 weeks of thrice-weekly IFN-alpha treatment (5 MIU), both in combinations with ribavirin. Sustained HCV clearance was observed in three patients. Nine patients discontinued the study aas a result of adverse reactions such as anaemia, pancreatitis and depression. In HIV/HCV-co-infected patients, the therapeutic benefit of high-dose IFN-alpha therefore seems to be limited by its poor tolerability.