The endothelin-B (ET) receptor is a key regulator of vascular endothelial function in women. We have previously shown that the ET receptor mediates vasodilation in young women, an effect that is lost after menopause. However, the direct impact of changes in estradiol (E) on ET receptor function in women remains unclear. Therefore, the purpose of this study was to test the hypothesis that E exposure modulates ET receptor-mediated dilation in young women. Fifteen young women (24±4 years, 24±3 kg/m) completed the study. Endogenous sex hormone production was suppressed with daily administration of a gonadotropin-releasing hormone antagonist (GnRHant; Ganirelix) for 10 days; E (0.1 mg/day, Vivelle dot patch) was added back on days 4-10. We measured vasodilation in the cutaneous microcirculation (microvascular endothelial function) via local heating (42°C) on day 4 (GnRHant) and day 10 (GnRHant+E) using laser Doppler flowmetry coupled with intradermal microdialysis during perfusions of lactated Ringer’s (control) and ET receptor antagonist (BQ-788, 300 nM). During GnRHant, vasodilatory responses to local heating were enhanced with ET receptor blockade (control: 83±9 vs. BQ-788: 90±5 %CVC, P = 0.004). E administration improved vasodilation in the control site (GnRHant: 83±9 vs. GnRHant+E:89±8 %CVC, P = 0.036). Furthermore, cutaneous vasodilatory responses during ET receptor blockade were blunted after E administration (control: 89±8 vs. BQ-788: 84±8 %CVC, P = 0.047). These data demonstrate that ovarian hormones, specifically E, modulates ET receptor function and contributes to the regulation of microvascular endothelial function in young women.