Goitrogenic a substance that can inhibit the taking of iodine by the thyroid gland, so that the concentration of iodine in the thyroid to be low., is characterized by the inflammation in the gland thyroid area caused an excessive of free radicals. An excessive of free radicals in the body cause oxidative stress, That increasing the levels of malondialdehyde (MDA) as an indicator of lipid peroxidation and decreased levels of urinary iodine excretion levels (EIU). The treated to give KIO₃ and KI salt was intended to determine the level of supplementation of iodine (I₂), the level of MDA in serum and histological rat thyroid gland. MDA levels are determined through a TBA test (Thio Barbituric acid), meanwhile the histological of the rat thyroid gland was determined by Hematoxylen-Eosin staining (HE). The results showed the KIO₃ and KI salt was significantly (p<0.05) reduce levels of MDA in the serum of treatment with KIO₃ salt (33.62%) and KI salt (37,02%) and improving histological of the thyroid gland rats.