Abstract: Estrogens exert important regulatory functions on vessel wall components, which may contribute to the increased prevalence and severity of certain chronic inflammatory and autoimmune diseases in females and the lower cardiovascular risk observed in premenopausal women. Endothelial cells have been recently identified as targets for estrogens, and estrogen receptors have been demonstrated in endothelial cells from various vascular beds. This review focuses on the regulatory function of estrogens in endothelial cell responses relevant to vessel inflammation, injury, and repair; estrogen effects on nitric oxide production and release; estrogen modulation of endothelial cell adhesion molecule expression; and estrogen regulation of angiogenesis. The mechanisms through which estrogen regulates endothelial cell functions are complex and involve both genomic and nongenomic mechanisms.