The pathogenetic role of thyrotropin-stimulation blocking antibodies (TSBab) in idiopathic myxedema has been described. Idiopathic myxedema is characterized as atrophic thyroid gland and positive autoantibodies to thyroid gland, including TSBab. TSBab is positive in 20-30% cases of idiopathic myxedema. TSBab is disappeared in some cases of TSBab positive idiopathic myxedema during treatment. In some of these cases, thyroid function recovered after the disappearance of TSBab. Transient neonatal hypothyroidism with TSBab positive was born in mothers of TSBab positive with autoimmune thyroid diseases. In these cases, thyroid function recovered with the disappearance of TSBab. Form these findings, it is suggested that TSBab may play a certain pathogenetic role in idiopathic myxedema.