Background: Treatment for Chronic Myeloid Leukaemia (CML) is mainly imatinib mesylate (IM) from original-brand, Glivec? or generic-type homologs, Imatib?. Materials and Methods: A collection of 149 CML patients was treated over a period of 6 years at Hiwa hospital. These patients were clustered into three groups: Group A was treated with Imatib for more than one year. All survivors of group A patients were switched to Glivec, classified as group B. Group C received only Glivec after June 2011. Imatib and Glivec are administered at doses 400-, 600- and 800-mg according to the CML stage. Results: Among group A patients, 68 (60%) were in complete haematological response (CHR), 32 (28.3%) developed acceleration and 13 (11.5%) patients were deceased. After switching to Glivec (group B), 69 (69%) patients remained in CHR, 10 (10%) patients weredeceased and 21 (21%) patients remained in acceleration. Of the 36 patients in group C, 33 (91.7%) were in CHR, 1 (2.8%) were in acceleration and 2 (5.5%) deceased. Those patients with CHR were tested randomly for BCR/ABL by FISH, and only 1/25 (4%) patients were found with complete cytogenetic response (CCyR) in group A, while 31/42 (73.8%) and 13/17 (76.5%) have CCyR in group B and C, respectively. Conclusions: Our results demonstrate a less cytogenetic response to treatment in patients of CML, who received the Imatib therapy, while a significant cytogenetic remission was found in patients with CHR after they switched to Glivec.