OBJECTIVES: To explore the chronic myeloid leukemia (CML)-related health care costs, utilizations associated with nonadherence and interruption of tyrosine kinase inhibitors (TKIs) in newly diagnosed CML patients. METHODS: This retrospective cohort study was conducted from 2003 to 2011 using the Taiwan Health Insurance Research Database. Newly diagnosed CML patients who received TKIs (imatinib, dasatinib and nilotinib) for more than one year during 2003 to 2010 were included in this study, and followed from the first TKI prescription date to death or end of study. CML-related medical utilization (number of outpatient and inpatient visits) and costs were calculated and stratified by TKI utilization pattern comparing interruption vs. persistence and non-adherence vs. adherence. Any gap between two consecutive prescriptions for more than 60 days and medicine possess ratio less than 80% were defined as interruption and non-adherence. Data were analyzed by generalized linear models with log link and gamma distributions. RESULTS: Of the 991 included patients, 24.6% and 15.8% were identified as interruption and non-adherence groups. Non-adherence and interruption rates were higher in patients who received increasing dose of imatinib, imatinib switched to dasatinib and imatinib switched to nilotinib. Adjusted outpatient cost per person year was higher in persistence (US$31,443±1,456) than interruption (US$22,071±1,163) group (p<0.0001); and higher in adherence (US$30,295±1,230) than non-adherence (US$18,259±1,050) group (p<0.0001). However, adjusted inpatient cost per person year was higher in interruption (US$5,674±1,665 vs. US$2,442±613; p<0.0001) and non-adhernece (US$6,390±1,866 vs. US$2,260±557; p<0.0001) groups. Likewise, CML-related inpatient visits per person year was higher in interruption (1.3 vs. 0.9; p=0.0093) and non-adherence (1.4 vs. 0.9; p=0.0251). CONCLUSIONS: Interruption and non-adherence to TKIs are associated with higher inpatient utilization and costs. Further study need to evaluate the clinical consequence and costs related to TKIs interruption and nonadherence for maximizing the efficiency of medical utilizations.