A liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for determination of tulathromycin in swine tissues has been developed. Prior to the instrumental analysis, the sample preparation technique involved extraction with a solution of meta-phosphoric acid followed by solid-phase extraction clean-up using a polymeric mixed-mode strong cation-exchange sorbent. The chromatographic separation was performed on a C8 chromatographic column with a gradient elution mode. Mass spectral acquisition was performed in selective multiple reaction monitoring mode by using a triple quadrupole mass spectrometer. The method has been characterized by providing the parameters of precision, accuracy, specificity, decision limit (CCα) and detection capability (CCβ) according to the Commission Decision 2002/657/CE. The calibration curves were linear in the range of 10–9000 μg kg⁻¹. The recoveries ranged from 92.9% to 102.1%. The repeatability was below 8.0% and the within-laboratory reproducibility was lower than 9.2%. The limits of detection ranged from 2 to 4 μg kg⁻¹ and the limit of quantification was 10 μg kg⁻¹. The presented analytical method can be used for measuring the tulathromycin depletion in swine tissues (kidney, liver and muscle) over time.