Autologous bone marrow transplantation is a therapeutic approach that permits the administration of high-dose chemo-radiotherapy followed by the infusion of the patient's own marrow, previously collected during remission and cryopreserved. In recent years, autologous bone marrow transplantation has been increasingly used as a treatment for acute leukemias. The mechanisms underlying leukemic relapse represent the most exciting and controversial aspects of autologous bone marrow transplantation. At least three factors may be responsible for leukemic relapse in patients receiving autologous bone marrow transplantation: (1) minimal residual disease; (2) leukemic cells reinfused with the graft; (3) the lack of a graft-versus-leukemia effect. In this paper, the techniques for pharmacological marrow decontamination and the clinical results obtained with autologous bone marrow transplantation will be reviewed.