Little is known about vitamin D and calcium metabolism in elephants. Domestic horses have historically been utilized as a model for elephant vitamin and mineral metabolism, however preliminary studies exploring calcium and vitamin D metabolism in elephants reveal possible differences from the equine model, as well as possible interspecies variation between Asian and African elephants.19,25,27 Furthermore, as a tropical herbivorous species, Asian elephants likely rely on cutaneous synthesis of vitamin D to meet their requirements. Thus, captive elephants living at high latitudes may be at significant risk for vitamin D deficiency, especially during winter months. Asian elephants, which are endangered in the wild, have poor reproductive success in captivity. Dystocia is an emerging problem in captive elephants, and recent literature suggests that hypocalcemia may be a significant factor in some cases.12,25Thus, establishing an understanding of normal calcium homeostasis, with the potential for reduction of morbidity and mortality in the perinatal period, is essential. Further characterization of elephant vitamin D and calcium metabolism will aid in the determination of elephant-specific nutritional requirements, contribute to the prevention of hypocalcemic-related disorders, and improve the health and welfare of captive elephants. This study will begin to explore vitamin D metabolism and its relationship to parathyroid hormone and calcium homeostasis in captive Asian elephants in the northeastern United States, utilizing the best available methods of analysis.