Leukemia is a cancer of marrow and blood, which is a clonal myeloproliferative disease, characterized by the presence of oncogenic Philadelphia chromosome, formed by a reciprocal translocation between chromosomes 9 and 22, resulting in the novel chimeric oncoprotein BCR/ABL. Chronic leukemia typically progresses slowly and permits the growth of greater numbers of more developed cells. If the cell change takes place in a type of marrow cell that normally goes on to form red blood cells, some kinds of white blood cells and platelets, the leukemia is called myeloid. Therapy for chronic myeloid leukemia depends on the stage of CML patient. After diagnosis and confirmation of CML positive patient, treatment available for patients includes imatinib that is an early diagnosed treatment for CML but after some duration of time, it may lead to resistance to imatinib treatment. Dasatinib, nilotinib, bosutinib & ponatinib can be used for the treatment of CML as secondary treatments. Ponatinib is also found effective against T315i mutation patients. Omacetaxine mepesuccinate can be given with a mechanism of action independent of tyrosine kinase inhibition. Clinical trial for development of advanced therapy, which includes combination therapy and newer developed a treatment against CML are going on. It is required to develop better drug therapy, which will not cause genetical mutation and drug resistant. It is also required to find out thecause of resistance and what are the possible ways by which better therapy for CML is possible.Keywords: Philadelphia (Ph) chromosome, chronic myeloid leukemia, Imatinib, Tyrosine Kinase Inhibitor (TKI), Haematological Response (HR), Cytogenetic Response (CR), Molecular Responses (MR), Reverse Transcriptase Polymerase Chain Reaction (RTPCR), BCR-ABL gene, T315I mutation, Imatinib-Resistanc
