Transient and definitive hypoparathyroidism represent a frequent complication after thyroid surgery. Recently some Authors proposed the use of intraoperative parathyroid hormone assay for the rapid detection of this complication. In this paper the Authors describe the data obtained from 42 total thyroidectomies with intraoperative measurements of parathyroid hormone. When parathormone decrement was over 75% during thyroidectomy, the hypocalcemic sintomatology was found in all cases during postoperative observation. The Authors enfatize intraoperative PTH dosage for immediate identification of patients at risk for postoperative hypoparathyroidism. In this cases parathyroid autotranslantation is suggested to prevent postoperative hypoparathyroidism.