The study was originally designed for lymphoblastoid α-interferon; then soon after trial approval by the NCI-Milan Scientific and Ethic Committee (#98-016) the protocol was amended for allowing also the use of recombinant α-2a (Roferon-A, Hoffmann-La Roche, Nutley NJ) or α -2b interferon (Intron-A, Schering-Plough, Kenilworth, NJ). The latter was eventually the preferred form. Patients allocated to treatment received IFN 3 MU/thrice weekly for 48 weeks starting within 6 weeks from the operation. The severity of adverse events during treatment were monitored and rated. Therapy was discontinued in case of life-threatening adverse event or in case of HCC recurrence during treatment. For severe events other than anemia the IFN dose was reduced by 50%; full dose could be resumed after the event was resolved or discontinued if the effect persisted. The percentage of the total predicted dose of IFN actually assumed by each patients was recorded. Patients assuming at least 80% of the total dose of IFN and treated for at least 80% of the expected duration of therapy were a priori defined as adherent to therapy.