Thyroid storm is a complication of thyrotoxicosis with a 20% to 30% mortality rate characterized by hyperthermia, tachycardia and altered mental status. Rarely, thyroid storm may have an apathetic presentation. The authors present a 63-year-old woman with apathetic thyrotoxicosis and hypercalcemia. The action of thyroid hormones stimulating bone resorption more than bone formation is thought to cause increased bone demineralization and, occasionally, hypercalcemia. This occurs in the absence of malignancy, prolonged immobility, hypervitaminosis D and primary hyperparathyroidism. Her thyroid storm was medically managed and her hypercalcemia was treated with intravenous fluids, calcitonin and a bisphosphonate. This case describes the presence of hypercalcemia in a patient with apathetic thyroid storm with no other factors contributing to the hypercalcemia. In addition, this patient had significant elevation in serum calcium, which possibly contributed to her symptomatology. The calcium remained normal after the thyrotoxicosis resolved, which is typical of the hypercalcemia of thyrotoxicosis.