The development of a method for the identification of ethyl esters of major fatty acids in poppy seed oil (ethyl palmitate, ethyl linoleate, ethyl oleate, ethyl linolenate) and their iodinated derivatives (iodoethyl oleate and iodoethyl linoleate) using high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) in electrospray ionization (ESI) positive-ion mode and multiple reaction monitoring (MRM) is reported. This analytical method for identifying fatty-acid ethyl esters and their iodinated derivatives is highly significant for medical science, serving as a key tool for the authenticity control of related products and the development of quantitative analysis methods for all components. In the future, this method could facilitate control in the development of new pharmaceutical formulations of medicines based on iodinated fatty-acid ethyl esters with improved properties and minimal risk of side effects. © 2025 Elsevier B.V., All rights reserved.