CML (chronic myeloid leukemia) is a cancer that affects bone marrow and blood. The diagnosis of CML is confirmed by presence of Philadelphia chromosome on cytogenetics or FISH or by detecting bcr-abl by PCR. It has 3 phases chronic, accelerated and blastic phase. Now we have drugs available that can durably control the disease these include imatinib, nilotinib, dasatinib, bosutinib, ponatinib, omacetaxine. These drugs produce rapid and durable response till the time they are continued and now trials are showing in carefully selected patients they can be discontinued with close monitoring. Bone marrow transplant is now reserved for patients who fail to respond to these tyrosine kinase inhibitor (TKI). The most common cause of resistence is development of a resistant mutation in the bcr-abl kinase domain. Most resistant is T315I mutation.