Imatinib mesylate (IM) is the first innovative molecule which emerged as a definitive therapy targeting bcr-abl gene of Philadelphia chromosome +ve chronic myeloid leukemia (CML). The use of this drug has carved a path for disease-free life. Though newer congeners have already arrived, the use of IM is still highest among the tyrosine kinase inhibitors (TKIs) in countries like India. This prospective, analytical study was carried out on the patients of CML in chronic phase at the department of haematology of S.C.B medical college and hospital with a study follow-up for two years. Data regarding bcr-abl protein breakpoint and progression of disease were recorded. Kaplan-Meier curve with Log rank test was used for time-to-event analysis. The overall progression-free survival (PFS) was 85.4% and the cumulative hazard of achieving major molecular remission (MMR) was 1.5. 94.1% of patients were having p210 break-point but 50% of the p190 breakpoint patients had disease progression. Though cases of resistance to IM have emerged and are a matter of concern, the efficacy profile is still quiet beneficial in Indian patients.