Eight patients with Ph1-positive chronic myelogenous leukemia (CML) in chronic or accelerated phase received high-dose cyclophosphamide, total body irradiation, and bone marrow transplantation from an HLA-identical sibling donor. All patients had prompt engraftment and achieved complete hematologic remission. Six patients remain alive and in continuous remission with a normal bone marrow karyotype 3-20+ mo posttransplant. One patient died from cytomegalovirus interstitial pneumonitis. Only one patient who was transplanted in accelerated phase relapsed 6.5 mo posttransplant and died in blast crisis. High-dose combined modality therapy is capable of producing sustained complete remissions in patients with CML treated during chronic or accelerated phase.