The study presented a case of a 54-year old woman who developed a fully symptomatic tetany syndrome with tachycardia and Chvostek's (++) sign during the initial 24 hours after subtotal strumectomy. Laboratory parameters demonstrated hypokalemia and hypocalcemia. After the intravenous injection of calcium chloride with simultaneous oral administration of alfacalcidiol, both the calcium and potassium levels returned to normal values.Postoperative tetany is observed in 0.2 to 5.8% of cases, according to literature data. Postoperative hypoparathyroidism may develop after total or subtotal thyroidectomy, as a result of the accidental excision of the parathyroid glands, their damage or vascularization. According to many authors postoperative hypoparathyroidism may result from the ligation of the lower thyroid artery, since these glands, both upper and lower, are supplied by blood in over 90% by the branches of these arteries. Other investigators maintain that tetany may also develop as a result of calcium metabolism disorders. Parathyroid ischemia may also result from pressure of the hematoma formed at the site of the removed thyroid lobes. The above-mentioned complication was probably influenced by a number of factors.