We report long-term outcome in 102 patients with cCML transplanted from an HLA-identical sibling donor from 1982 to 1998. The conditioning regimen was based on cyclophosphamide associated with either total body irradiation (TBI) (37 patients) or with busulfan (63 patients). Graft-versus-host disease (GvHD) prophylaxis consisted of cyclosporin and methotrexate in the majority of the patients. Fifteen year overall survival was estimated at 53% (95% confidence interval (CI), 44-65) with a plateau after 2.5 years. Long-term survival was adversely affected by longer time from chronic myeloid leukemia (CML) diagnosis to transplantation, older age at time of transplantation and GvHD (acute grade III-IV or chronic extensive). The main cause of death was infection, related to GvHD in 69% of patients. Splenectomy also significantly increased the risk of bacterial infection. 15-year relapse was estimated at 8% (95% CI, 0.1-14). Late malignancies occurred in seven patients, four of whom had an invasive cancer. Other frequent late complications included cataracts, psychological depression, osteonecrosis and hypothyroidism. These complications were more frequent following splenectomy, TBI and in patients with chronic extensive GvHD. We conclude that allogeneic transplantation with a related donor can cure more than half of CML patients in chronic phase, although physicians should be alert to long-term complications.