We treated 500 patients with high-dose chemotherapy and autologous bone marrow or autologous peripheral blood stem cell transplantation. Treated conditions included leukemia, lymphoma, breast cancer, lung cancer, germ-cell carcinoma, and other solid tumors. 10/500 (2%) of patients were treated for a second malignancy diagnosed 12 months to 25 years after their initial neoplasm. Four of these ten patients are in complete remission (CR) of both malignancies at a median follow-up of 29+ months after high-dose chemotherapy and autotransplantation. None of these patients would have been eligible for high-dose chemotherapy and autotransplantation by conventional selection criteria which usually excluded patients with a history of prior malignancies. Conclusion. Conventional exclusion criteria for high-dose chemotherapy and autotransplantation may not adequately reflect the prognosis of patients with second or secondary malignancies treated with this therapeutic modality. High-dose chemotherapy and autologous hematopoietic stem cell transplantation may be of true benefit in selected cases of secondary malignancies.