Autoimmune thyroiditis are common and benign disorders, affecting preferentially women, at any age of life. They may occur singly or integrated as a part of familial predisposition to autoimmune thyroid disease or autoimmune polyendocrinopathies. Clinical presentation is variable: goiter or thyroid atrophy, euthyroid or temporary or permanent hypothyroidism, rarely transient thyrotoxicosis. Commune features are the presence of antithyroperoxydase antibodies and lymphoplasmocytic infiltrate of the thyroid parenchyma. It is important to distinguish the cases in which thyroid dysfunction is transient and requires only monitoring and those in which hypothyroidism is permanent and justifies thyroid hormone replacement. In the forms with goiter, clinical and ultrasonic control of the thyroid is justified.