Bone marrow transplantation (BMT) is an intensive mode of treatment for acute leukemia of childhood. Indication are types and stages of leukemia with a poor prognosis following chemotherapy, such as acute nonlymphocytic leukemia (ANLL) in first complete remission (CR) of the disease, and acute lymphocytic leukemia (ALL) following relapse of the disease, in second CR. On the basis of our own experience and of analysis of published data it can be stated that allogeneic BMT, grafting bone marrow cells from a healthy HLA-identical sibling of the patient, has a long-term therapeutical effect which is superior to that of chemotherapy alone: in cases of ANLL, grafted in first CR, a long-term disease-free survival of 55 to 67% was obtained, and in cases of ALL, grafted in second CR, this was between 38 and 64%. The potential effect of autologous BMT, i.e. with own bone marrow of the patient, sampled during CR of the disease, cannot yet be evaluated properly, because the follow-up period of this mode of treatment is too short. It is worth while to investigate the potential beneficial effect of autologous BMT, e.g. for children with ALL in second CR, who lack a HLA-identical donor. Also the potential contribution of bone marrow purging, e.g. for CALLA-positive lymphocytes, should be investigated in relation to the relapse risk after autologous BMT for common ALL.