The purpose of the present study was to evaluate the feasibility and the efficacy of employing a high-dose chemotherapy (HDT) regimen with tandem peripheral blood progenitor cells (PBPC) supported transplantation in the initial treatment of aggressive non-Hodgkin's lymphoma (NHL). HDT was preceded by a standard course of conventional dose chemotherapy in 17 out of the 25 patients treated, while in 8 cases it was delivered after only one or two cycles. HDT was a three-step procedure which included high-dose (6-7 g/m2) cyclophosphamide (CY) supported by haematopoietic growth factors, the first myeloablative course with mitoxantrone (NOV) 60, 75 or 90 mg/m2 plus melphalan (L-PAM) 140-180 mg/m2 with haematopoietic rescue, and the second myeloablative course with etoposide (VP) and carboplatin (CARBO) given at 1.5 g/m2 each with haematopoietic rescue. PBPC were collected after CY administration. Twenty-two patients (88%) completed the HDT, haematological reconstitution was rapid and complete at each step and there were no toxic deaths. The activity of the treatment was high with a CR rate over 90% in the entire patient population. The 2-year overall survival (OS) and failure-free survival (FFS) rates of patients in both Age-Adjusted International Prognostic Index (A-AIPI) groups 2 and 3 are 79% and the disease-free survival (DFS) rate for the CRs is 85%. In A-AIPI group 1 the 2-year OS and FFS rates are both 91%.