Over the past ten years several centers have studied bone marrow transplantation following high-dose chemotherapy and radiation in patients with resistant acute leukemia. These data indicate a 10-20% two-year disease-free survival; results superior to alternative approaches. Leukemic relapse and graft-versus-host disease have been major problems. Recently, marrow transplantation has been evaluated in patients with leukemia in remission. This has resulted in improved survival in patients with acute lymphoblastic leukemia but leukemic relapse remains a major problem. Acute myelogenous leukemia patients transplanted in remission have a low rate of leukemic relapse and two-year disease-free survival rates exceeding 50%. Recently, autologous bone marrow transplantation has also been considered in patients with acute leukemia. Results to date have been disappointing with a high relapse rate. Limited studies in patients with chronic myelogenous leukemia have also been reported. Transplantation during the acute phase is usually unsuccessful and is complicated by incomplete engraftment and resistant leukemia. Transplants performed during the chronic phase have produced more encouraging results. In summary: there is an evolving role for bone marrow transplantation in the treatment of patients with acute and chronic leukemia. A final evaluation of the utility approach awaits results of controlled clinical trials.