Abstract A low level of selenium (Se) in the blood and serum of Finns was demonstrated. Inhabitants in the central, eastern and southeastern districts of the country had particularly low levels selenium. However, the Se level of Lapps and the people of the Åland archipelago seemed to be significantly higher than the level of other Finns. In general, the Se levels in the serum were lower than the values for whole blood. Furthermore, the levels were lower in children than in adults. The significance of these findings in the pathogenesis of some human diseases is discussed.