A number of recent reports have now shown that hematopoietic stem cells are present in the circulation, and these cells have the potential to restore complete hematopoiesis following marrow aplasia. Peripheral stem cells have been collected by continuous flow leukapheresis during periods of hematopoietic regeneration after 2 to 3 weeks of intensive chemotherapy. Following marrow ablative chemotherapy or chemoradiotherapy, the autologous peripheral stem cells are thawed and infused intravenously. When a sufficient stem cell dose was given, rapid neutrophil and platelet recovery has been confirmed, as compared with bone marrow transplantation. Acute leukemia, malignant lymphoma and solid tumors may benefit from this approach, and long-lasting remission or cure may result in a significant number of patients.