The patient who has congenital hypothyroidism and pseudohypoparathyroidism could have mental retardation even though adequate hormone treatment and cannot endure conventional dental treatment. In this case, general anesthesia is selected to administer effective dental treatment. But, there could be symptoms such as anemia, neuropathy, associated pituitary or adrenal hypofunction, cardiac failure even in euthyroid state. And, bradycardia, mental dullness, hypothermia, slow reflexes can appear in case of inadequate thyroid hormone replacement. Especially, macroglosssia, slow drug metabolism, exaggerated responses to anesthetic agents and decreased ventilatory responses could be problem during general anesthesia. The presentation of hypoparathyroidism also varies depending on the chronicity of the result of hypocalcemia. Muscle spasms/tetany, paresthesias, and seizures may occur in an acute onset. Chronic hypocalcaemia causes fatigue, muscle cramps, lethargy, personality changes, and cerebration defects.