Myxoedema coma is life threatening emergency of decompensated hypothyroidism, recognition of hypothyroidism may not always be easy in the emergency department setting. Laboratory evaluations of thyroid function are not usually performed on a 24-hour basis, and therefore the emergency physician, although suspecting the presence of hypothyroidism, may be unable to confirm the diagnosis while the patient is in the Emergency Department. Treatment consists of correction of electrolyte abnormalities, passive rewarming, treatment of infections, respiratory and hemodynamic support, administration of stress-dose glucocorticoids, and thyroid hormone replacement.