A combination of prednimustine 100 mg/m2/day orally, days 1-5, and mitoxantrone 8 mg/m2/day intravenously, days 1 and 2, was administered to 19 patients with advanced low-grade non-Hodgkin's lymphoma after failure on or relapse after standard chemotherapy. The prednimustine and mitoxantrone (PmM) regimen was repeated every 4-6 weeks to a maximum of six cycles. Thirteen patients, achieving a complete (4) or partial (9) remission (CR or PR), received two additional courses for consolidation followed by interferon alfa-2b 5 million units (MU) subcutaneously (s.c.) three times weekly until progression or relapse. At the present time, remission duration ranges from 4.5+ to 17.5+ months, with a median of 14.5 months. In a historical comparison to unmaintained first remission preceding the PmM/interferon trial, a tendency towards a longer period of freedom from progression was apparent in the 13 patients receiving interferon maintenance treatment during their second PR or CR. These data provided the basis for a currently ongoing multicentre study randomly comparing initial chemotherapy with PmM versus cyclophosphamide/vincristine (Oncovin)/prednisone (COP) in patients with advanced centroblastic-centrocytic and centrocytic non-Hodgkin's lymphomas, followed by a second randomization in CR and PR patients for maintenance with alpha interferon versus observation only.