The aim of this study was to investigate factors of mineral nutrition influencing growth and composition of skin derivates and their content in blood plasma of horses. The thesis describes three experiments carried out on Czech warm blood breed horses on Boudky farm, Velké Němčice. In the first experiment was analysed the effect of fed supplement mixture -- vitamins, methionine and organic form of zinc and copper -- on growth rate and mineral composition of hoof horn and hairs and level of trace elements in blood plasma. The effects of copper and zinc in their organic and inorganic form on parameters above were evaluated in the second and third experiment. The addition of supplement mixture to experimental group led to significant increasing (P<0.01) level of zinc in dry matter of hoof horn from 95.82 +- 8.96 mg.kg-1 to 117.73 +- 10.23 mg.kg-1 and copper (P<0.05) from 2.39 +- 0.75 mg.kg-1 to 4.06 +- 1.14 mg.kg-1 during the first experiment. No differences were found between initial and final levels of minerals in hairs. In the second experiment, mares receiving copper sulphate deposited significant higher (P<0.01) copper level into hairs 17.39 +- 2.32 mg.kg-1 than the mares of control group 13.37 +- 1.82 mg.kg-1. The results of mares receiving copper in organic form did not significantly differ from the previous two groups. There was found out significantly decreased (P<0.05) levels of zinc content in dry matter of hair from 153.56 +- 10.46 mg.kg-1 to 139.68 +- 7.09 mg.kg-1 in the mares receiving of zinc oxide and in the mares of control group from 154.59 +- 17.03 mg.kg-1 to 136.33 +- 6.96 mg.kg-1 (P<0.05) during experiment. The growth rate of skin derivates was influenced only by using supplement mixture -- vitamins, methionine and organic form of zinc and copper and was not influenced with individual application of copper or zinc. Growth rate of hoof horn in the mares receiving this supplement was significantly higher (P<0.01) about 22.31 % than in the animals of control group. The same results was found in the mane hairs (P<0.01). The growth rate of hairs was about 15.37 % higher in the horses from experimental group than from the control one.