Calciphylaxis is an uncommon and often devastating syndrome of calcification of small vessels, leading to tissue infarction. The mechanism of how calcium deposits on small vessels is unknown. Recently, metalloproteinase digestion of elastin has been shown to enhance deposition of calcium, suggesting a possible mechanism of calciphylaxis. We describe a case of a patient who developed calciphylaxis after rapid weight loss, but had normocalcemia and normal renal function. She was found to have high levels of matrix metalloproteinases, which may have chemically altered elastin, allowing deposition of calcium on small vessels. Inhibitors of matrix metalloproteinases may be useful in the prevention and treatment of calciphylaxis.