Grave hypercalcemia may complicate primary hyperparathyroidism. This clinical condition is potentially life-threatening, if it is untreated. The emergency therapy consist in rehydratation, stimulation of diuresis and somministration of biphosphonates. A urgent surgery is required if conservative theraphy is not successful. The Authors herein present a consecutive serie of 6 cases with acute hypercalcemic crisis due primary hyperparathyroidism, successful treated with urgent parathyroidectomy after conservative treatment.