Hypoparathyroidism is the most common complication of thyroid surgery. Accurate treatment of this condition requires early diagnosis of patients at risk of hypocalcemia.The aim of the study was to evaluate the predictive value of intraoperative parathyroid hormone assessment in identification of affected subjects.Material and methods. Sixty five subjects participated in the prospective study. They underwent bilateral neck exploration with subtotal or total thyroidectomy. Parathormone (PTH) and calcium levels were assessed prior to surgery, intraoperatively and at different time-points following the operation.Results. In respect of the results, patients were allocated into 3 groups: (A) subjects with asymptomatic course; (B) subjects with perioperative symptomatic hypocalcemia; (C) subjects with prolonged symptomatic hypocalcemia. No differences between these groups were observed in the intraoperative calcium levels. Intraoperative parathormone (ioPTH) level was significantly lower in group C and at value minor of the reference range identified group C subjects with sensitivity and specificity of 100 and 91.5%, respectively. Mean intraoperative PTH level decrease (ΔioPTH) of 22.5% was observed. ΔioPTH rate was significantly higher (81.4%) in group C. This parameter presented sensitivity of 66.7% and specificity of 93.2% in identification of group C patients.Conclusions. Single intraoperative PTH level assessment identifies subjects at risk of postoperative hypoparathyroidism. Intraoperative drop of PTH (ΔioPTH) proves less sensitive. Intraoperative calcium levels cannot be regarded as a predictor of this complication.