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An effective liquid chromatography-tandem mass spectrometry method was developed for monitoring 3,3’,5,5’-tetraiodothyronine (T4), 3,3’,5-triiodothyronine (T3), and 3,3’,5’-triiodo-l-thyronine (rT3) in meat tissue and egg. In this method, iodothyronines are extracted with acetonitrile and the extract is cleaned by passage through an Oasis MAX cartridge. Chromatographic separation on a C-18 column is achieved by gradient elution using 0.1 % acetic acid and acetonitrile. Ion detection was done with positive electrospray ionization and multiple reaction monitoring (MRM). Pork, beef, chicken, cod, salmon, and whole egg were used for validation, and the data show the method is selective and sensitive (limit of detection (LOD) a parts per thousand currency sign0.04 ng g(-1)), with acceptable accuracy (recovery 81.2-123.1 %) and precision (relative standard deviation (RSD) 2.3-20.1 %) for the three analytes in meat tissue and egg. An investigation with a small number of sample size indicated rT3 was below the limit of detection in most samples analyzed (pork, beef, chicken, egg white, egg yolk, cod, and salmon). T3 and T4 in egg were found mainly in the yolk. T4 was the most abundant iodothyronine in pork, beef, chicken, and egg; by contrast, T3 was the most abundant iodothyronine in fish. Among the samples tested, the highest level of T4 was found in egg yolk and the highest level of T3 was found in salmon.