Oligocrine is a preparation of vegetable origin characterized by anti-inflammatory, antioxidant, immunomodulating properties. Our study shows that administration of L-thyroxine injections (irrespective of the duration) results in elevated synthesis of thyroid hormones and intensification of oxidative stress in experimental animals. These changes are evidenced by accumulation of membrane phospholipide peroxidation products - lipid peroxides in the blood. At that we should point that while dependence of FT3 and FT4 levels on the duration of L-thyroxine administration was insignificant in the experimental model of thyrotoxicosis, intensity of lipid peroxidation increased along with prolongation of injections. Blood levels of free nitric oxide were decreased likely due to the transformation of nitric oxide into peroxinitrite. Oligocrine facilitates to the stabilization of thyroid status and restriction of NO hyperproduction, hypermetabolism and oxidative stress in the body.