Bone marrow autotransplantation involves the administration of very high doses of chemotherapy or radiation therapy, or both, followed by infusion of autologous hematopoietic stem cells. This treatment was used in the past as a salvage therapy for patients with end-stage cancers. Occasional cures in patients with chemotherapy-responsive malignancies encouraged oncologists to utilize this treatment earlier when a better result might be achieved. This has led to a substantial number of long-term disease-free survivors in non-Hodgkin's lymphoma, Hodgkin's disease, acute leukemia, and neuroblastoma. Studies are currently ongoing in the treatment of breast cancer, multiple myeloma, testicular cancer, and ovarian cancer. Important areas for future investigation include the identification of optimal criteria for patient selection and timing of the therapy, the need for infusion of hematopoietic stem cells as cloned hematopoietic growth factors become available, the identification of the most effective high-dose regimens, and the need for "purging" tumor cells from the marrow before re-infusion. Successfully addressing these issues will increasingly require large comparative trials.