The antioxidant system of blood is the important factor that characterizes the adaptive possibilities of human organism. The estimation of state of the antioxidant protection and lipid peroxidation systems at men and women of two Baikal Lake ethnic groups was carried out. Spectrophotometric and fluorometric methods were used during the study. Increase of by-products of lipid peroxidation with decrease of activity of the antioxidant protection system was observed at men of the Buryat ethnicity in comparison with Russian ones. At women of the Buryat ethnicity was observed the increase of the primary products of lipid peroxidation with the adequate antioxidant response in comparison with Russian ones.