The levels of thyroid hormones are important indicator of metabolic activity. The knowledge of the metabolic activity in different physiological periods, animals readjusted dietary regimen. Therefore, in this study, changes of triiodotironine (T3) and thyroxine (T4) hormones in the blood serum of female (n=14) and male (n=9) white goats were studied for a duration of one year through different physiological periods [breeding (September-October), gestation (November to March), postpartum-sucking (April-May) and milking (June to August)]. Results show that the differences in T3 and T4 hormone levels between sexes are statistically unimportant in breeding, gestation, postpartum-sucking and milking periods, while the changes for each sex between the physiological periods are important (p<0.05). Also, it has been found out that the thyroid hormone levels in different physiological periods are under the influence of the environmental temperature changes.