OBJECTIVES: To estimate the cost of care for CML in patients with resistance and/or intolerance to imatinib from the public perspective in Mexico METHODS: Retrospective study of 208 patients diagnosed with CML, ≥18 years of age, treated with imatinib and having at least 12 months follow-up with final contact in the past three months, whom were attended at 6 tertiary level public hospitals in Mexico. Cost of care data captured includes drug costs (chemotherapy and imatinib), inpatient visits, toxicity treatment, and medical monitoring (labs studies, outpatient visits and other drugs costs). Costs are estimated on a monthly basis and are classified according to the presence of failure (toxicity or resistance to imatinib). Descriptive statistics on the use of resources are reported. RESULTS: At diagnosis of CML, 95% of patients were in chronic phase and 5% in accelerated phase. Fifty-five percent were female, with a mean age of 48.30. Defining treatment failure as any imatinib dose adjustment, increasing if resistance (lack of hematological and/or cytogenetic response) or reduction if intolerance (toxicity), 84.7% of patients failed initial treatment with imatinib. The median time to imatnib dose adjustment was 5.1 months. The average monthly cost of diagnosis and treatment prior to receiving imatinib was estimated US$2,210.54 ($2461-$2808); the average monthly cost during treatment of imatinib and prior to failure was estimated US$2793 ($1612-$3125). The average monthly cost after failure increased to US$4706.18 ($3642-$5770), which represents an increment of 68.5% (t-test p<0.001). The cost drivers of the increase are primarily:  1) inpatient visits, which increase from US$180 pre-failure to USD$367 post-failure, and 2) resources used in medical monitoring and CML treatment, which increase from US$3678 pre-failure to US$4338 post-failure per month. CONCLUSIONS: Once patients are resistant or intolerant to imatinib, their cost of treatment increases through additional demand for medical resources at Mexican public health care institutions.