Murine progressive ankylosis (MPA) is characterized by periarticular ossification and joint ankylosis. We studied calcergy and calciphylaxis in MPA. Calcergy represents a chemical attraction betwen heavy metal salts and apatite followed by hydroxyapatite deposition around collagen Mice were injected subcutaneously with FeCl2, PbAcetate, and saline, and sacrificed at intervals between 5 minutes and 14 days. Section of skin and subcutaneous tissues were stained with Von Kossa's stain. No mice developed calcifylaxis. PbAcetate produced calcergy in all mice. MPA mice exhibited calcergy qualitatively and quantitatively the same as normal mice suggesting abnormal calcergy is not responsible for joint ankylosis in MPA.