Purpose: This work aimed to evaluate the impact of a guaranteed access program to Imatinib on the survival of patients with Chronic Myeloid Leukemia Methods: We carried out a retrospective, observational, and analytical study of the database of patients diagnosed with Chronic Myeloid Leukemia of the Instituto Nacional de Cancerología and the Hospital General de México Dr. Eduardo to assess overall survival based on guaranteed access or not to Imatinib. Results: With an average follow-up of 99 months, the estimated 20-year overall survival for all patients was 72% (95% CI, 76-67). A significant difference was found in the 20-year survival probability in favor of patients with guaranteed access 76% (95% CI, 81-71) vs. 61% (95% CI, 69-52) (p<0.001), in addition to those in which they had better attachment 81.2% (95% CI, 85-76) vs. 44.9% (95% CI, 52-37) (p<0.001). Conclusion: CML is the most frequent chronic leukemia in Mexico, it mainly affects the economically active population (mean age 40), and the prognosis in our country has improved, emulating developed countries; however, the results depend on access to treatment as well as proper monitoring.