In the present study, platelet GSH_(px), SOD activities and cAMP contents, as well as whole blood, erythrocyte, plasma and hair selenium levels were comparatively measured in children from Keshan disease endemic and non-endemic areas. The results showed that blood and hair selenium contents were significantly lower in children of the endemic area than in those of the non-endemic area; children in the endemic area had a signifi cantly lower platelet GSH_(px) activities as compared to those in the non-endemic area, but no remarkable difference of platelet SOD activities and cAMP contents between children in the two areas was observed. The results indicate that the reduced GSH_(px) activity of low-selenium children in the endemic area may result in alterations in platelet functions and arachidonic acid metabolism.