Only a minority of all patients with CML can today be treated by allogeneic bone marrow transplantation (BMT) but the probability of cure for such patients is high. The complications of BMT are similar to those that occur following transplant for other diseases, notably GVHD, pneumonitis and infections. Of special interest is the demonstration that a graft-versus-leukaemia effect plays a role in the cure of CML. Studies using the polymerase chain reaction to detect minimal residual disease (BCR/ABL transcripts) may prove useful in predicting relapse and optimizing conditioning schedules. It is now important to test whether BMT can be equally successful in older patients (over 50 years) and in those lacking HLA-identical sibling donors. For other patients autografting may offer the possibility of achieving complete cytogenetic remission and perhaps prolonging life.