Acute primary hyperparathyroidism is a rare disease with a high mortality rate in some series. Between 1960 and 1986, 1000 patients were treated for primary hyperparathyroidism, among them 59 patients with acute hyperparathyroidism. All these patients were successfully operated on; none of them died before surgery. This study reveals the importance of resuscitation and urgent surgery. It is necessary to rehydrate, to correct electrolyte disorders and to lower serum calcium levels, but it is not necessary to obtain normal serum calcium levels before surgery.