Fifteen patients from a series of 37 consecutive patients with aggressive NHL who achieved a complete remission (CR) with first line chemotherapy were defined at high or high-intermediate risk of relapse according to International Prognostic Risk Index and were treated with alpha IFN as maintenance therapy for two years. After a median follow-up of 62 months only 3/15 patients (20%) relapsed and 2/15 (13.3%) died in the alpha IFN treated group, favourably comparing with the expected relapse and death rate in that setting; on the other hand 40.9% of 'low risk' patients from the same series, who did not receive alpha IFN, had relapsed. alpha IFN maintenance therapy appears to result in prolonged response duration and survival in patients with aggressive and prognostically unfavourable NHL.