A female infant who was anoxic at birth had lesions of subcutaneous fat necrosis at the age of 16 days. She also had problems with poor feeding, frequent vomiting, and failure to thrive. Hypercalcemia was discovered at the age of 28 days and she died at 11 1/2 weeks despite return of the serum calcium level to normal with oral prednisone therapy and a diet low in calcium and devoid of vitamin D. Fourteen other cases of idiopathic hypercalcemia in patients with subcutaneous fat necrosis of the newborn have been reported. Most of these infants were full-term with prenatal complications. The hypercalcemia was usually diagnosed much later than the subcutaneous fat necrosis. Both conditions generally resolved without sequelae, but two of the 14 infants died. The causal relation between these two entities, if one exists, remains unknown. Infants with subcutaneous fat necrosis should have serial serum calcium determinations and should be observed closely for signs and symptoms of hypercalcemia, which include irritability, anorexia, constipation, and failure to thrive.