The effects of selenium and fatty acid supplementation on fatty acid composition and antioxidant status of erythrocyte membrane in lambs were investigated. Thirty two lambs with average body weight of 26±1 kg were divided into 4 groups and each was fed basal diet+5% linseed oil (LO), or LO+2 mg Se/ kg DM (as sodium selenite) (LOSe), or basal diet+5% sunflower oil (SO), or SO+2 mg Se/kg DM (SOSe). Selenium supplementation increased the concentration of C18:2t-10,c-12, and also the concentration of C20:5n-3 of erythrocyte membrane of the lambs fed the sunflower oil diet. Lambs fed the linseed oil diet had higher concentrations of C18:2t-10,c-12, C18:3n-3, and C20:5n-3 in erythrocyte membrane. Erythrocyte membrane of the lambs fed sunflower oil diet had higher concentrations of C18:1t-11, C18:2n-6, C18:2c-9,t-11 and C22:6n-3. Antioxidant status increased with selenium supplementation, and lambs fed sunflower oil diet had higher total antioxidative capability.