Almost 10 years after the first report of the effectiveness of interferon (IFN) for chronic NANB hepatitis, the optimal treatment for chronic hepatitis C is still a matter of debate. The issue of the relative importance of higher doses versus a longer period of therapy remains unsettled, since the long-term response may be a function of the total dose received. Controlled studies have shown that high doses of IFN (5-6 MU t.i.w.), a long period of therapy (> 12 months) and the administration of a large total dose are all associated with a higher cure rate. However, these measures can cause more adverse effects and certainly cost more than the current schedule of 3 MU t.i.w. for a period of 6 months. The standard schedule may be appropriate for subjects with pre-treatment features predictive of a good response (non-Ib genotype, low viraemia, absence of cirrhosis). Alternative treatment schedules or combination therapy with interferon/ribavirin should be considered in subjects with normalized alanine aminotransferase (ALT) levels, but who are still viremic after three months of therapy, as well as in relapsers and in non-responders.