In the experiment with 12 horses of Czech Warmblood, an influence of a nano-form of zinc on growth of hoof keratin was tested. There were not found any difference in growth of hoof keratin between experimental and control groups. The control group was given a supplement with zinc oxide. The concentration of zinc tended to by higher (for 5,69 mg/kg of DM) when given in the nano-form whereas in comparison with the content of zinc before the beginning of the experiment, increasing of its content was found (the control group = 60,63 vs. the experimental group = 73,07 mg/kg of DM).