Unsustainable drug prices in chronic myeloid leukemia (CML) and cancer may be causing harm to patients. The aim of this multi-center study is to assess the efficacy of generic imatinib mesylate (IM) over Glivec in terms of hematological, cytogenetic, and molecular responses in CML. The data of 120 CML patients, who were treated with generic or original form of IM, were obtained from six different hematology clinics in Turkey between the years of 2009-2014 and analyzed retrospectively. Initial evaluation revealed that only one patient who was using original molecule switched to second generation tyrosine kinase inhibitor (TKI). In this period, hematological response(HR) was observed in 99.2% of the patients, cytogenetic response (CR) was observed in 88.7% of the patients (47 of 53), and molecular response (MR) was observed in 75% of the patients. Clinicians had a tendency to prefer generic molecules in each sequent visit, and this switch rate was statistically significant (p<0.001). 11 patients, who were using original molecules during all cohorts, switched to second generation TKI. On the other hand, only one patient, who was using generic molecules, switched to second generation TKI. Our paper may help to clarify the doubts about the efficacy of generic IM compared to original molecule. In our study we did not find any significant difference in HR, CR, and MR for original and generic drugs in each visit. Herein, we find low rates of need to switch to second generation TKIs with generic IM and no difference in treatment responses between generic and original molecules that confirms the non-inferiority of generic TKIs over original molecules.