Postoperative hypocalcaemia is one of the important complications of thyroidectomy. It is observed within 2-5 days postoperatively, and its incidence is more common after total thyroidectomy than after conservative thyroidectomies. When hypocacaemia is associated with hypomagnesaemia, this may render the symptoms more resistant to treatment. This requires correction of both ions. The meticulous dissection and preservation of parathyroid glands and their intact blood supply decrease the incidence of postoperative hypocalcaemia.