Selenium (Se) is a non-metallic element, which has the capability to increase the antioxidative capacity and stress tolerance of plants to heavy metals. Plants vary considerably in their physiological response to Se. The reported research investigated the effects of Se on arsenic (As) uptake by As hyperaccumulator Pteris vittata L. and determined possible mechanisms of interaction. Pteris vittata plants were exposed hydroponically to 0, 150 or 300 mu M of Na(2)HAsO(4) in the presence of 0.5 or 10 mu M of Na(2)SeO(4) for 5 or 10 d. Application of 5 mu M Se enhanced As concentration by A vittata fronds by 7-45%. At 5 mu M, Se acted as an antioxidant, inhibiting lipid peroxidation (reduced by 26-42% in the fronds) via increased levels of thiols and glutathione (increased by 24% in the fronds). The results suggest that Se is either an antioxidant or it activates plant protective mechanisms, thereby alleviating oxidative stress and improving arsenic uptake in P. vittata. Published by Elsevier Ltd.