Advances over the last several years have led to a better understanding of the etiology of hyperparathyroidism in renal disease and to more effective means of medical prevention and therapy. Thus, in most dialysis populations, many of the serious complications, such as bone fractures, refractory hypercalcemia, and hyperphosphatemia with vascular and other extraskeletal calcifications, have diminished. Furthermore, more aggressive medical management has decreased the requirement for parathyroidectomy. Unfortunately, not all patients respond to medical management and few still develop refractory hyperparathyroidism with associated morbidity. Of the many complications of refractory hyperparathyroidism in dialysis patients, the development of life-threatening hypocalcemia has not been described. We describe a patient with severe secondary hyperparathyroidism who presented with the acute development of hypocalcemia. To our knowledge, this represents the fourth case, the first reported in a patient with end-stage renal disease, of parathyroid autoinfarction presenting as acute hypocalcemia.