The adrenal gland plays an essential role in regulating homeostasis in the body through the secretion of corticosteroid and androgen hormones. The secreted steroids arise from the three zones of the adrenal gland: the zona glomerulosa, zona fasciculate, and zona reticularis. Microvascular endothelial cells (MEC) line the blood vessels and contribute to many biological processes; such as hemostasis, coagulation, trafficking of lymphocytes, and the inflammatory response. MEC regulate the secretion of adrenal hormones in the adrenal gland. Studies have shown that factors secreted from HAdMEC, such as endothelin-1, nitric oxide, adrenomedullin and proadrenomedullin NH2-terminal 20 peptide affect aldosterone secretion. HAdMEC, unlike brain and liver MECs, are highly resistant to glucocorticoid-induced cytotoxicity. Human Adrenal Microvascular Endothelial Cells are usefull tools for understanding physiological and pathophysiological relevance in adrenal gland function and disease.