In the course of hyperthyreosis reactive oxygen production increases and oxidative stress develops. The consequences of oxidative stress comprise disturbances in balance of pro- and antioxidative agents, including changes in concentration of antioxidative vitamins and microelements. Although the results of published studies concerning changes of concentrations of vitamins and microelements in hyperthyreosis are contradictory, most frequently a decrease of zinc and magnesium concentrations was observed.