The current study examined the relationship between a prognostic indicator of vascular health, flow-mediated dilation (FMD), and working memory-related brain activation in healthy middle-aged adults. Forty-two participants underwent functional magnetic resonance imaging while completing a 2-Back working memory task. Brachial artery endothelial-dependent flow-mediated dilation (FMD) was assessed using B-mode ultrasound. The relationship between FMD and task-related brain activation in "a priori" regions of interest was modeled using hierarchical linear regression. Brachial FMD, was significantly related to reduced working memory-related activation in the right superior parietal lobule (@b=0.338, p=0.027), independent of age, sex, systolic blood pressure, and full scale IQ (F(5,36)=2.66, p=0.038). These data provide preliminary support for the association between a preclinical marker of endothelial dysfunction and cerebral hemodynamic alterations in healthy middle-aged adults. Considering the modifiable nature of endothelial function, additional investigations on the prognostic significance of FMD on future cognitive impairment are warranted. (Contains 3 tables and 2 figures.)