Imatinib mesylate, a selective inhibitor of the ABL tyrosine kinase, has revolutionized the treatment of chronic myelogenous leukemia (CML) due to its high level of activity, low toxicity, and durability. Five-year data from the pivotal trial of imatinib, the IRIS trial, suggests durable responses in a high proportion and reduction and almost elimination of the incidence of imatinib failure over time. The imatinib dose of 400 mg is considered to be standard based on the IRIS trial. Recently, new tyrosine kinase inhibitors (TKI) have been developed, which can overcome imatinib resistance, and comparative studies between each TKI and imatinib are ongoing for imatinib-resistant CML and newly-diagnosed CML. TKI will be chosen based on the profiles of mutation of the ABL kinase domain. On the other hand, the results of hematopoietic stem cell transplantation in patients treated with imatinib were reported, and pretreatment of imatinib did not influence TRM. However, the optimal dose, duration of imatinib treatment and the indication of reduced intensity conditioning transplantation have not been established. Longer follow-up, the accumulation of results of the new TKI therapy and HSCT are required.