We evaluated the therapeutic efficacy of autologous bone marrow transplantation (ABMT) in 49 patients with acute leukemia, using ex-vivo-treated marrow with mafosfamide. This report summarizes data collected from 8 italian centers, involving 27 cases with acute lymphoid leukemia (ALL) and 22 cases with acute nonlymphoid leukemia (ANLL). The analysis of the results shows that the disease-free survival of ALL and ANLL are similar (45 and 52%, respectively) and no significant difference can be demonstrated between patients transplanted in CR1 or CR2, although there is a trend in favor of ABMT in CR1.