Chronic Myeloid Leukemia is the first malignant disorder with a specific genetic abnormality in the background. Known as a disease with an inexorable progression to acute leukemia for many years, its natural history has been dramatically improved by the use of tyrosine kinase inhibitors (TKI). They represent the first molecular targeted therapy addressed to a neoplastic disorder. From these new classes of drugs, Imatinib was the first drug ever used, and it remains the standard therapy for patients in chronic phase with CML, having a global survival of 86%, for 7 years. The 2nd generation of TKI (Dasatinib, Nilotinib) is indicated for the patients who are refractory or intolerant to Imatinib. The other TKI have good promises to be efficient on the mutations of BCR–ABL transcript, especially to non–responsive T315I mutation. The new era of molecular target therapy is a new hope of life for all cancer patients.