The functional viability of cryopreserved human parathyroid tissue was assessed by determining suppressibility of parathyroid hormone release by evaluation of ambient calcium concentration. Parathyroid hormone release from dispersed human parathyroid cells prepared from both fresh tissue and tissue cryopreserved for up to 200 days was suppressed 0-90% in response to four-fold increases in calcium concentration. In the tissue that demonstrated suppression precryopreservation, the suppression curve was similar in form postcryopreservation. The ability to retain functional integrity within human parathyroid cells by cryopreservation, allows preservation for periods of time probably sufficient to determine the presence of the aparathyroid state, and allows for subsequent successful parathyroid autotransplantation. This technique has particular applicability to patients reoperated upon for persistent hyperparathyroidism where the remaining amount of normal parathyroid tissue is obscure or unknown.