Autologous blood stem cell transplantation (ASCT) was performed in 32 patients with high risk chronic myelogenous leukemia (CML). Prior to ASCT, the patients were given Busulfan and high-dose Melphalan. Peripheral blood stem cells collected at diagnosis were used to rescue hematopoiesis. Recombinant Interferon was administered after ASCT. In 24 patients transplanted in transformation, 23 achieved a complete hematological response and nine are still alive 9 to 73 months after ASCT. Eight other patients were transplanted in chronic phase for either the presence of bad prognostic factors (Sokal's classification) or no response to IFN. Seven are alive without transformation 16 to 48 months after ASCT. Although few patients presented a cytogenetical response (10/28), the survival observed in this series of patients compares favorably with that of patients treated conventionally. Thus, the place of ASCT in CML could now be tested prospectively.