The toxicity and potential late side effects of total body irradiation, especially in children, have caused the evaluation of alternative myeloablative agents. We report the results obtained in 4 patients with acute myelocytic leukaemia, 2 patients with acute lymphocytic leukaemia and 1 patient with chronic myelocytic leukaemia who received high-dose busulfan followed by bone marrow transplantation (4 times allogeneic, 3 times autologous), according to the protocol published by G. W. Santos. 4 patients have survived 708+, 413+, 313+ and 234+ days, respectively, to date, 3 patients died, two of whom had acute myelocytic leukaemia in relapse and died of cardiac and combined organ failure 9 and 10 days post transplantation, respectively, without evidence of leukaemic cells in the bone marrow. One patient with acute lymphocytic leukaemia (T-All) in second remission died of an extramedullary relapse 485 days after bone marrow transplantation. We report our experience in the use of busulfan before transplantation not only in patients with acute myelocytic leukaemia, but also in patients with acute lymphocytic leukaemia and chronic myelocytic leukaemia and discuss the effectiveness and toxicity of high-dose busulfan as alternative to total body irradiation.