Brachial artery flow-mediated dilation (FMD) is a validated, non- invasive physiological measure widely used as a research tool to quantify endothelial function, as pointed out in the study by Calermajer, et al. According to Moens, et al, FMD is diminished in patients with several coronary risk factors, is an independent predictor of cardiovascular events, and improves with risk reduction therapy. Thus, there are numerous studies on FMD and cardiovascular disease, vascular risk factors, or endothelial dysfunction therapy. In contrast, the usefulness of FMD in ischemic stroke is little known and has been poorly studied. However, FMD could also be of great usefulness in ischemic stroke such as stroke subtype classification, prognostic significance in acute phase, and independent predictor for new-onset vascular event after first-ever stroke. In this review article, brachial artery FMD and its role in ischemic stroke is discussed extensively.