As a trace elementselenium is an essential micronutrinet and has important benefits for human and animals, but its essentiality has not been proven yet for higher plants. The specific physiological mechanisms that are responsible for positive effects in plants, primarily in antioxidant defense, have not yet been clarified. Selenium has dual effect on plants, in low concentrations acts as an antioxidant, while in higher concentrations acts as a pro-oxidant. The aim of this study was to determine how different forms and concentrations of selenium influence the antioxidant system, especiallyactivities of glutathione reductase and catalase in the shoots of wheat (Triticum aestivum L.) cv. Divana. Wheat was treated with three different concentrations of two forms of Se (selenite and selenate). All concentrations of both selenium forms did not activate catalase. On the other hand, only the two highest selenate concentrations caused increase in glutathione reductase activity, while selenite did not have such an effect what can be connected with more efficient mobility of selenate in upper parts of plants. Obtained results can serve as a basis for fruther research of the effects of higher selenium concentrations on the various antioxidant systemcomponents.