the Czech Republic, low soil selenium (Se) contents followed by insufficient soil-plant-animal transport of this element have been previously reported. Therefore, the attention of animal nutrition experts should be focused more intensively on the Se status in grazing animals. The experiment was carried out on 42 horses from two locations, A and B (21 animals per group), where the animals are used for sport or recreational purposes, respectively. The Se contents in soil, selected plants, individual components of the diet and animal whole blood were determined. The soil Se contents varying between 0.233 and 0.507 mg · kg⁻¹, confirmed low Se contents in the Czech soils. Similarly, the Se contents in plants were low and did not exceed 0.07 mg · kg⁻¹ of dry matter (result of low Se mobility in the investigated soils), whereas the levels of other essential micronutrients, such as copper, iron, manganese and zinc, occurred in the sufficient concentrations. The Se contents in the whole blood of animals varied between 0.044 and 0.215 mg · l⁻¹ and were comparable with the results of many other similar studies conducted across the Europe. The adequate Se status in animals can be strongly related to the high Se contents in complementary feedstuffs such as pellets and muesli, whereas feeding animal diets based only on roughage and grain produced at the investigated farms could be Se deficient. Therefore, the supplementation of horse diet with Se is recommended in the Czech Republic.