The study is conducted on Thoroughbred stallions. The first stage covered the study of the elemental composition (20 elements) of stallion hair (n=148) raised in the southeast of Russia (Stavropol Territory, Krasnodar Krai, Volgograd and Rostov regions). On the basis of obtained results 10, 25, 75, 90 percentile intervals of concentration of the main essential and toxic elements in hair were established. At the second stage, the stallions raised on the farms of Stavropol Territory (n=29) and Krasnodar Krai (n=32), as well as Rostov (n=24) and Volgograd (n=28) regions were examined. Hair samples were selected from mane area in the first cervical vertebra projection. Proximal part of hair (15 mm long) was selected from the hair root for analysis. The elemental analysis of samples was made via inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled mass spectrometry (ICP-MS). It is established that the hair of stallions raised in Stavropol Territory had the highest concentration of Al, As, Sn and Hg at a reliable difference (p≤0.05) with similar indicators for species from Krasnodar Krai. The typical feature of animals raised in Volgograd Region was the maximum concentration of Cd, Pb and Sr fixed against the background of the minimum Cr, I, Mn and Se values. All studied micro-populations were characterized by the excess of established norms of toxic metals. The most considerable deviations (2.5-6.9 times) of aluminum, mercury and tin were typical for animals raised in Stavropol Territory. The species from Krasnodar Krai had lower concentration of zinc. The assessment of the frequency of deviations of the element status from the norm showed that the zinc content in the hair of 48.3% of examined animals from Stavropol Territory and 50.0% of species from Rostov Region made more than 75%. A large number of species from Krasnodar Krai was characterized by the lack of iodine (46.9%) and selenium (34.4%) against the background of the minimum values of cadmium (50.0%) and mercury (100%).