Aging is associated with an increased prevalence of thyroid diseases. The diagnosis of overt hypothyroidism and hyperthyroidism may be difficult since they are often pauci- or monosymptomatic. Subclinical forms of thyroid diseases, in particular hypothyroidism, are even more frequent. Therapeutic abstention with regular follow-up is usually recommended in hypothyroidism. Radical treatment is usually preferred for subclinical hyperthyroidism since heart complications may be severe. Increased prevalence of benign and malignant nodules is observed in the elderly. The prognosis of thyroid cancer is less favorable than in adults, due to a higher proportion of histological types with a worse evolution. Whatever the thyroid disease, diagnosis and treatment modalities should be adapted to the age and general conditions of the patient. Contradictory results have been reported on the relationship between thyroid status and neuromuscular and cognitive alterations linked to aging.