Allogeneic hematopoietic stem cell transplantation (HSCT) is well-established as 
a potentially curative treatment for patients who have chronic myeloid leukemia. 
The success of imatinib and other tyrosine kinase inhibitors (TKI) as initial 
therapy has changed the treatment paradigm for this disease. Allogeneic 
hematopoietic transplants are now reserved for patients whose disease does not 
respond optimally to TKI treatment. Patients whose disease does not have an 
optimal response to imatinib may respond to a second-generation TKI, dasatinib 
or nilotinib, and many achieve major or complete molecular and cytogenetic 
responses. The indication for allogeneic HSCT versus continued second-line 
therapy is not well-defined and is the subject of ongoing study. There has been 
continued progress in reducing the toxicity and risks of HSCT with development 
of reduced-intensity regimens; transplants can be routinely performed in 
patients up to the age of 75 years who are in fair general medical condition. 
Transplantation results from unrelated donors have improved, with survival rates 
similar that achieved with matched siblings. Results with haploidentical and 
cord blood transplants have markedly improved, and should be considered for 
patients lacking a matched donor. Allogeneic hematopoietic transplants have the 
best chance to be curative in patients with chronic phase that is under 
hematologic control with 80% disease-free survival; patients progressing to the 
accelerated phase or blast crisis have a much poorer prognosis. Thus, HSCT 
should be considered for patients with imatinib failure. Patients receiving 
second-line TKI therapy must be closely monitored and referred for 
transplantation if a complete cytogenetic response and major molecular response 
is not achieved. HSCT should be performed if feasible in patients without a 
continued response to TKI treatment.