To prevent postoperative hypoparathyroidism following total thyroidectomy, the parathyroid glands are preserved in situ and/or resected or devascularized parathyroid glands are autotransplanted. We conducted a retrospective investigation utilizing biochemical and specific endocrine assessments to evaluate the difference in recovery of parathyroid function between the two operative methods. A total of 92 patients underwent total thyroidectomy at our hospital during the period between 1990 and 1997. These patients were divided into a preservation group (n = 83), with one or more preserved glands in situ, and an autotransplantation group (n = 9), with only transplanted glands. The level of intact parathyroid hormone (PTH) was completely restored by 1 year postoperatively in 83% (69/83) of the preservation group patients. In the remaining 14 patients (17%), the intact PTH had fallen below detectable levels on postoperative day (POD) 1, then subsequently recovered to 70% of the preoperative levels. Comparatively, in the autotransplantation group, the mean level of intact PTH recovered to only 43% of the preoperative levels. The results of this study suggest that parathyroid glands should be preserved in situ whenever possible, and that when intact PTH levels fall below detectable limits on POD 1, they may never recover to the preoperative levels in those patients.