Aim: To assess CML patient's characteristic including demographic, clinical and hematological characteristic of patients with CML including quantitative BCR-ABL and BCR-ABL gene sequencing. Methods: This study was an open-label, single arm, non-randomized, cross sectional study in patients with CML being treated with imatinib mesylate (IM) from 12 centers. Result: A total of 100 patients were evaluated between January 1, 2009 and December 31, 2011. The median age was 34-35 years old (mean of age is 36 years old), and more patients in the productive age was found.-(?) were 80 of the 100 patients who had been examined for the BCR-ABL gene mutation with the sequencing method before consuming IM. Mutation in the P-loop was seen in 2,27% (1 out of 44 patients), this finding was beyond our expectation since 47,69% (31 out of 65 patients) of our patients did not achieved CHR at three months. On the other hand, 15,9% (7 out of 44 patients) of our patients had mutation outside the P-loop. Conclusions: The characteristics of CML patients in Indonesia were not different from CML patients in Asia in general. Our finding concerning the high frequency mutation in the BCR-ABL gene outside the P-loop needs further study.