Background: Pseudoxanthoma elasticum (PXE), an inherited disorder of unknown pathogenesis, is characterized by elastic fiber mineralization, collagen fibril alterations, and accumulation of thread material in the extracellular space. PXE-like clinical lesions have been described in patients with β-thalassemia. Objective and Methods: Dermal lesions in these two genetic disorders were compared by light and electron microscopy and by immunocytochemistry. Results: In both disorders, elastic fiber polymorphism, fragmentation, and mineralization were structurally identical. Elastic fiber mineralization in β-thalassemia was associated with vitronectin, bone sialoprotein, and alkaline phosphatase, similar to what was observed in inherited PXE. Furthermore, abnormalities of collagen fibrils and filament aggregates were identical in both disorders. In both inherited and β-thalassemia-associated PXE, unrelated gene defects seem to induce cell metabolic abnormalities that lead to identical clinical and structural phenotypes. Conclusion: Data indicate that patients with β-thalassemia may undergo important alterations of connective tissues, a better understanding of which may help in preventing clinical complications. (J Am Acad Dermatol 2001;44:33-9.)