IDIOPATHIC hypoparathyroidism is one of the rarer abnormalities of endocrine function in childhood. For that reason it may be missed on occasion because it is not considered among the diagnostic possibilities. There have been 6 cases of idiopathic hypoparathyroidism seen at the Harriet Lane during the past 10 years and the youngest child of this series was 17 months when admitted. This child's symptoms may have begun in the neonatal period and this may be true of other children with hypoparathyroidism. An apparently authenticated case of congenital hypoparathyroidism has been reported by Rhyne and also by Calcagno and Rubin. The etiology of this disease is completely obscure. There is ordinarily no story of multiple cases in families, except for a group of cases in which there has been a strange combination of moniliasis, hypoparathyroidism and in some instances adrenal insufficiency. The possibility that severe moniliasis may produce toxic injury to parathyroid and adrenal glands has been suggested, as has been the converse notion that the spread of monilia infections is facilitated by the biochemical disturbances of hypoparathyroidism. Among the 6 cases in our series only 1 has shown obvious moniliasis and this has not been of the extraordinarily severe degree reported in the literature. Some type of seizure either focal or generalized is the usual manifestation which brings the child to the physician. The seizures may persist for several years without becoming more severe and may be treated as epilepsy. One of the patients in this series was admitted at the age of 15 years.