The aim of the work was to determine the effect of dietary As additions (39.6 m g As2O3/g) on tissues Se and I concentration of 49 weeks old Rhode Island Red laying hens. After 19 days blood was collected by anterious heart puncture and after slaughter following organs were collected: liver, kidney, lung, muscle (musculus pectoralis superficialis) and plumage. Se and I concentration were determined with radiochemical neutron activation analysis and the results were expressed on dry matter basis. In trial group the most Se concentration was found in kidney, followed by liver, blood, lung, muscle and plumage. In trial group the most I concentration was found in plumage, followed by kidney, lung, liver, blood and muscle. Added As in the feed significantly increased Se concentration in lung, I concentration in muscle and it significantly decreased I concentration in blood.