In January, 1925, Collip and Leitch1reported marked clinical improvement in a case of infantile tetany treated by the administration of an extract of parathyroid glands. The method of preparation and the properties of this extract were later more fully described by Collip and his associates.2Hjort, Robison and Tendick,3working independently, confirmed the efficacy of the extraction method and duplicated many of the animal experiments. Since the time when a preparation of this parathyroid hormone became available for experimental study, only four cases of infantile tetany have been seen in the clinic. The data from this small number of cases are insufficient to justify any general conclusions. The primary purpose in presenting the figures is to make them available to other clinics at the beginning of the season when infantile tetany increases in frequency, thus eliminating for them some of the preliminary work on dosage. METHODS