Very high-dose cytotoxic therapy requiring bone marrow transplantation is the most active treatment for most hematologic malignancies and appears to be the treatment of choice for most patients with these diseases at relapse. Autologous bone marrow transplantation and allogeneic bone marrow transplantation can generally be expected to yield similar results in patients with lymphoma or acute leukemia; autologous bone marrow transplantation offers the advantage of greater availability and less toxicity but with a higher rate of tumor recurrence. Novel approaches that can increase the antitumor activity of autologous bone marrow transplantation without increasing the toxicity are being investigated. Dose intensification followed by autologous marrow rescue is also very active against responsive solid tumors, eg, breast cancer, ovarian cancer, testicular cancer, and pediatric solid tumors. However, it is difficult to demonstrate that autologous bone marrow transplantation has yet to lead to an improvement in disease-free survival for patients with solid tumors. Therefore, the exact role autologous bone marrow transplantation should play in the treatment of solid tumors remains to be established.