Sixty patients with Chronic Myeloid Leukemia (CML) who were on oral imatinib were included in this study. The study aimed to evaluate patients' characteristic, tolerability and efficacy and clinical outcome in Iranian patients who have been treated with generic imatinib. The median age of patients was 48 years, and the median follow up was 44 months. 94% of patients achieved complete hematologic response (CHR) during the 3 months of beginning imatinib, and after 12 -24 months of imatinib therapy 46.8% achieved molecular response. The most common non-hematologic toxicity was fluid retention (64%), fatigue (43%) and moderate to severe hematologic side effect included anemia 10%, neutropenia 10%, and thrombocytopenia 6.6%. About 13% of patients transformed into accelerated phase (AP) or blastic crisis (BC) and the death rate during this period was 7%. In conclusion, there is heterogeneity in different areas in characteristic of CML (especially in age), and also response rate and side effect of patients with CML that treated with imatinib are different.