Targeted therapy of Philadelphia chromosome-positive chronic myeloid leukemia (CML) using the tyrosine kinase inhibitor imatinib mesylate has been one of the most striking achievements in modern cancer medicine. However, while imatinib can establish long-term remission in many cases, resistance to or intolerance of imatinib is eventually experienced by a substantial number of patients. Subsequent advances have led to the development of novel tyrosine kinase inhibitors (TKIs). One such inhibitor, nilotinib, was rationally designed to increase its affinity and specificity for the oncogenic tyrosine kinase Bcr-Abl compared with imatinib and has been shown to be effective after imatinib failure. Recently, nilotinib has been shown to be more effective when used as first-line therapy of chronic phase CML.