Blood stem cell transplantation has become an important treatment modality for the complete cure of chronic myelogenous leukemia (CML). Favorable factors for the success of transplants are: (1) young patients, (2) treatment within 1 year of diagnosis, (3) CML in the chronic phase, (4) an allogeneic transplant from a matched sibling (BMT). Interferon treatment may be another effective therapy, however, it is not yet confirmed whether it can produce a complete cure or not. The most serious problem with BMT is considered to be early death. Informed consent and selection of treatment by the patient is very important.