Oral disorders were observed in children with congenital hypothyroidism, lately apparent because of difficulties of feeding, swallowing disorders, and macroglossia. Macroglossia was also a component of the severe acquired myxedema, particularly observed in hypothyroidism related to autoimmune atrophic thyroiditis beyond menopause. Lingual ectopy in children and adults could determine respiratory gene or swallowing difficulties, and were detectable by visual examination and the endobuccal touch. Expression of these events was completely minimized since the neonatal screening of congenital hypothyroidism, also by the common practice in adults of serum TSH determinations. Congenital and acquired hormonal deficits are now early detected and correct with suppletive doses of levothyroxine. Oral expression of hyperthyroidism is poor, even if thyrotoxicosis is sometimes revealed by increased thirst. Caution is required for dental care, mainly due to changes in the hemostatic functions. Finally, a genetic predisposition to the medullary thyroid cancer may be revealed by an oral and neuromatosis. Radioisotopic therapy of thyroid cancers is likely to alter the salivation., (Copyright © 2017. Published by Elsevier Masson SAS.)