This study examined the utility of therapeutic drug monitoring (TDM) of imatinib, nilotinib, and dasatinib in adult patients with chronic-phase chronic myeloid leukemia (CML). TDM in CML entails the measurement of plasma tyrosine kinase inhibitor (TKI) concentration to predict efficacy and tolerability outcomes and to aid in clinical decision making. TDM was to be deemed useful if it could be used for predicting the effectiveness of a drug and/or the occurrence of adverse reactions. It was expected that the findings from the present study would allow for the definition of a therapeutic range of each TKI. A systematic review of studies reporting trough TKI levels (Cmin) and clinical outcomes was performed. We included randomized clinical trials, nonrandomized controlled studies, interrupted time series studies, and case series studies that provided information about plasma levels of imatinib, nilotinib, or dasatinib and relevant clinical end points in adult patients with chronic-phase CML treated with the corresponding TKI as the single antiproliferative therapy. Meta-analyses, Student t tests, and receiver operating characteristic analyses were performed to detect mean differences between groups of patients with or without: (1) the achievement of major molecular response and (2) adverse reactions. A total of 38 studies (28 for imatinib, 7 for nilotinib, and 3 for dasatinib) were included in the systematic review. TDM was found useful in predicting the efficacy of imatinib, with a Cmin cutoff value of 1000 ng/mL, consistent with guideline recommendations. We suggest a therapeutic range of imatinib at a Cmin of 1000-1500 ng/mL because higher concentrations did not increase efficacy. The findings from the rest of the comparisons were inconclusive. TDM is useful in predicting the efficacy of imatinib in CML. Further research is needed to determine its validity with nilotinib and dasatinib. Copyright © 2019 Elsevier Inc. All rights reserved.