Primary hyperparathyroidism is rarely produced by parathyroid carcinoma. We present the case of a 63-yr-old man who was admitted due to recent onset of constipation, weakness and progressive lethargy. At physical examination, a left cervical mass was palpated. Marked hypercalcemia (serum calcium 25 mg/dl) (6.22 mmol/l) complicated by renal insuficiency (serum creatinine 4.4 mg/dl) (388 micromol/l) was found, but both were unresponsive to conventional therapy and hemofiltration. Autopsy examination showed a carcinoma of the upper left parathyroid gland, multiple foci of metastatic calficications in the vessel walls and parenchyma of both lungs and kidneys, and the myocardium, which contributed to multi-organ failure and death. In addition to describing the clinical presentation, we review the mechanism of metastatic calcifications as well as the role of renal function and hyperphosphatemia, and the basis for therapy of hypercalcemic crisis.