For more information regarding BMS clinical trial participation, please visit www.BMSStudyConnect.com. Inclusion Criteria: - Newly-diagnosed chronic phase chronic myeloid leukemia (CP-CML) patients who started their first-line Tyrosine Kinase Inhibitor (TKI) treatment on imatinib, dasatinib or nilotinib in accordance with the timelines below - 18 years or older at time of of CP-CML diagnosis a) Imatinib Cohorts - Patients who started their first-line Imatinib treatment between January 2, 2008 and September 30, 2010.Patients fitting this criterion are defined as retrospective Imatinib patients − Patients who started their first-line Imatinib treatment on or after October 1, 2010 b) Dasatinib Cohort - Patients who started their first-line Dasatinib treatment after the drug was approved in this indication c) Nilotinib Cohort - Patients who started their first-line Nilotinib treatment after the drug was approved in this indication - Patients are also eligible when they have already switched to a subsequent therapy (TKI or other) at the time of enrollment, as long as their first-line and subsequent CML treatment information is available at site for data entry into the study Electronic Case Report Form (eCRF) - Receiving treatment at medical practice (eg. community-based, office-based, hospital-based, academic setting, oncology center) Exclusion Criteria: - Patients who are participating in an interventional trial which may influence the management of their CML disease will be excluded Discontinuation Criteria: - Enrolled patients who join an interventional trial which may influence the management of their CML disease will be excluded at the time of entry into the interventional trial