Allogeneic BMT from histocompatible-related and -unrelated donors can provide curative therapy for a variety of hematologic, oncologic, immunologic and hereditary diseases. Obstacles to successful outcome of allogeneic BMT include GVHD, disease relapse, opportunistic infection and toxicity of the conditioning and GVHD prophylaxis regimens. As these problems are surmounted, the number of BMT survivors is expected to steadily increase and the QOL post-BMT will become as important as the duration of survival in evaluating the outcome of allogeneic BMT. High-dose chemotherapy or chemoradiotherapy, followed by ABMT or autologous peripheral blood stem cell transplant has been shown to produce long-term, disease-free survival in patients with relapsed, refractory and poor-risk HD and NHL. Despite the success of ABMT and PBSCT in treating these diseases, the short- and long-term transplant-related mortality continues to be a major concern and mandates exploration of new approaches to reduce acute and delayed fatal toxicities. ABMT as post-remission therapy for adult AML has yielded results similar to those achieved with allogeneic BMT. The role of bone marrow purging and posttransplant immunomodulation in preventing disease relapse after ABMT is being investigated.