Hungry bone syndrome is a unusual complication of the postoperative period of primary hyperparathyroidism. This syndrome is characterized by hypocalcemia, hypophosphatemia and hypomagnesemia, due to an excessive bone remineralization. We report the clinical features, laboratory and therapy in four females (aged 39 to 73 years old) with a long standing hyperparathyroidism, elevated alkaline phosphatases and decreased bone mineralization in two. The mean size of the adenoma was 2.9 ± 1.1 cm. Hypocalcemia appeared between days 1 and 6 of the postoperative period. All were treated with calcium, calcitriol and magnesium at different timing and dosages. The mean hospitalization period was 19.8 ± 2.1 days. As reported previously, low bone mineralization and a large adenoma are risk factors for the syndrome. Serial monitoring of serum calcium and magnesium and an early supplementation of these minerals could prevent hypocalcemia and decrease the hospitalization time. (Rev Méd Chile 2000; 128: 80-85)