In our work it was studied the metabolic reactions in adolescent girls representatives the two small nationalities (Tofalars and Evenki) and alien (Caucasians) of the population living in different areas of the Irkutsk region. It is found the hypothalamo-thyroid adaptive response development (increase in free T3 concentration, and decrease of TSH in Tofalars; and higher levels of total T4 and T3 in Evenki) in comparison with Caucasians. The study of antioxidant defense system demonstrated the increased content of a-tocopherol and retinol in Tofalars and only retinol in Evenki. The analysis of these two systems relationships revealed the correlation between the thyroid status and antioxidants (T3-α-tocopherol axis) in Evenki and Tofalars. This data proposed that indicated metabolic changes revealed in Tofalars and Evenki may be the result of genetically-determined long-term adaptation to the region environment conditions.