Nilotinib is a selective inhibitor of BCR-ABL approved for use in newly diagnosed and imatinib-resistant or -intolerant patients with chronic myeloid leukemia (CML) in chronic phase. In this study, 400 mg of nilotinib was administered twice daily to the patients with myeloid (MBP, n=105) or lymphoid blastic phase (LBP, n=31) CML. After a minimum follow-up of 24 months, major hematologic responses were observed in 60% (MBP) and 59% (LBP) of patients. Major cytogenetic responses (MCyR) were attained in 38% (MBP) and 52% (LBP) of patients; and complete cytogenetic responses in 30% and 32%, respectively. Median duration of MCyR was 10.8 (MBP) and 3.2 months (LBP). Median overall survival was 10.1 (MBP) and 7.9 (LBP) months with 12- and 24-month survival of 42% (MBP 44%, LBP 35%) and 27% (MBP 32%, LBP 10%), respectively. Twelve MBP patients and two LBP patients received subsequent stem cell transplantation. Myelosuppression was frequent, with grade 3/4 neutropenia, thrombocytopenia, and anemia in 68%, 63% and 47% of patients, respectively. Grade 3/4 hypophosphatemia, hyperbilirubinemia and lipase elevation were observed in 15%, 11% and 11% of patients, respectively. Nilotinib has significant efficacy in patients with BP CML, but given the limited long-term survival of these patients, novel agents are needed.