For chronic myeloid leukemia (CML) patients, tyrosine kinase inhibitors (TKI) adherence is crucial in achieving optimal response. The study examines the association among TKI out-of-pocket costs, adherence, and healthcare costs and utilization in a large group of commercially insured CML patients. CML patients aged 18 to 64 were identified using Truven Health MarketScan® Commercial Claims and Encounters data between 1/1/2011 and 12/31/2015. Patients were required to be continuously enrolled 3 months before and 12 months following TKI (imatinib, dasatinib, nilotinib, bosutinib, or ponatinib) initiation. TKI adherence is estimated using the proportion of days covered (PDC), defined as the percentage of the proportion of days covered by the prescription fill during the 12-month study period (adherent patients have PDC≥80%). Healthcare cost differences between adherent and non-adherent patients were estimated using generalized linear models. Healthcare utilization was compared using negative binomial regression models. All models were controlled for potential confounding factors. The study sample consisted of 867 patients, where 357 (41.2%) patients were classified as adherent. Patients with higher TKI out-of-pocket costs (≥75th percentile in the distribution of costs) for a 30-day supply have lower predicted PDC by 2.4% (p<0.001). Over the study period, non-adherent patients incurred $11,181 more in medical costs (p<0.001) and $1,662 more in non-TKI pharmacy costs (p=0.049). Adherent patients were estimated to be less likely to have inpatient admissions (IRR=0.32; p=0.000), or hospitalizations for CML (IRR=0.30; p=0.005). CML patients with lower TKI out-of-pocket costs were more adherent and experienced lower healthcare utilization, resulting in medical service cost savings.