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Imatinib, dasatinib, and nilotinib are tyrosine kinase inhibitors (TKIs) used as first-line treatment of chronic myeloid leukemia. Therapeutic drug monitoring is important to achieve treatment efficacy in the case of imatinib and nilotinib, and to control toxicity in the case of dasatinib. New high-sensitivity methods to monitor those drugs are needed, especially for dasatinib. Thus, a simple method to determine plasma levels of imatinib, dasatinib, and nilotinib for application in clinical practice was developed.TKIs were eluted with a Poroshell 120 EC-C18 column (2.1 × 75 mm, 2.7 μm) at 0.5 mL/min and 60°C, under gradient conditions through a mobile phase consisting of 4 mmol/L ammonium formate, pH 3.2 (65%), and acetonitrile (35%). TKIs were detected and quantified by liquid chromatography in tandem with mass spectrometry (LC/MS–MS) with positive electrospray ionization and analytes were extracted using solid phase extraction (Versaplate-SCX). Internal standards were isotope-labeled for each analyte.The method was linear in the range of 2.5–5000 ng/mL for imatinib, 0.75–400 ng/mL for dasatinib, and 2–4000 ng/mL for nilotinib. The validation assays for accuracy and precision, matrix effect, extraction recovery, carryover, and stability of the samples for all the TKIs were appropriate according to regulatory agencies. Furthermore, imatinib plasma samples, stored for 4 years at −80°C were quite stable in approximately half of the samples.The method enables rapid quantification of TKI concentrations and is being applied to therapeutic drug monitoring to adjust dose and to manage adverse reactions in clinical practice.