The aim. The aim of this work was to conduct a microscopic and phytochemical study of the seeds of chia (Salvia hispanica L.). Materials and methods. Chia seeds were examined macroscopically and microscopically. To study the qualitative composition of the main groups of biologically active substances, histochemical, microchemical and chemical reactions were used. Hydroxycinnamic acids were identified by paper chromatography. To obtain a lipophilic extract, a Soxhlet apparatus and an exhaustive chloroform extraction method were used. The study of the quantitative content of fatty acids was carried out by gas chromatography. The content of polysaccharides in the raw material was determined by the gravimetric method. According to the SPhU method, the raw material swelling index was determined. Results. The main macro- and microscopic features of chia seeds have been established. Histochemical reactions, microchemical reactions made it possible to establish the presence of mucus and fatty oils in chia seeds. With the help of chemical reactions, the presence of flavonoids in the raw material was established. The quantitative content of fatty oils is 24.0±1.2 %. The content of water-soluble polysaccharides in the whole raw material was 4.01±0.07 %, in the crushed raw material - 5.04 ± 0.05 %. As a result of determining the swelling index, it was found that this indicator for the whole chia seeds was 20, and for the crushed ones – 17. The content of hydroxycinnamic acids in the chia seeds was 1.07±0.03 %. 9 fatty acids have been identified, among which linoleic acid predominates in terms of content. Conclusions. The presence and quantitative content of mucus, fatty oils, water-soluble polysaccharides, flavonoids, hydroxycinnamic acids, fatty acids was confirmed in the seeds of chia (Salvia hispanica L.). The obtained data can be used to develop regulatory documentation for chia seeds in order to use this raw material in pharmacy and medicine