• CMML;
  • allogeneic marrow transplantation;
  • myeloproliferative disorder;
  • risk factors;
  • cure

We evaluated the outcome of allogeneic bone marrow transplantation (BMT) in 21 patients with chronic myelomonocytic leukaemia (CMML) who were treated at the Fred Hutchinson Cancer Research Center between 1990 and 1998. There were 11 male and 10 female patients with a median age of 47·4 years (range 1·0–62·9). Patients were conditioned either with total body irradiation (TBI) and chemotherapy, with or without antithymocyte globulin (n = 19), or with chemotherapy alone (n = 2). The marrow donor was an HLA-identical sibling in 12 patients, an HLA-non-identical related donor in three patients and an unrelated volunteer donor in six patients. All evaluable patients achieved sustained engraftment. Fifteen patients developed grades II–IV acute graft-versus-host disease (GVHD). Nine patients (43·0%) are surviving disease free at 0·7–8·1 years (median 6·9) after transplantation. Five patients relapsed 75–660 d after transplant and all died. Five patients died with organ failure and two died with GVHD and associated infections. The Kaplan–Meier estimates of disease-free survival and relapse at 3 years were 39% and 25% respectively. The probability of survival was improved in patients with shorter disease duration compared with those with a long interval from diagnosis to BMT. Thus, as with other myeloproliferative diseases or myelodysplastic syndromes, BMT offers curative therapy for a proportion of patients with CMML. We suggest that patients with CMML who have a suitable donor should be considered for transplantation, probably early in their disease course. However, it will be important to develop new regimens with enhanced antileukaemic efficacy without further increasing regimen-related toxicity and mortality.