Aim It has been demonstrated that brief episodes of mental stress can cause transient endothelial dysfunction, which is an important early event in atherogenesis. The purpose of this study is to examine the independent effect of hostility trait on resting endothelial function. Objective A total of 89 healthy adults were recruited. Hostility was measured by the Buss-Durkee Hostility Inventory- Chinese Version- Short Form. Vascular dilatory functions were measured by using ultrasound imaging of the brachial artery before and after cuff occlusion, before and after sublingual nitroglycerin. Conclusion Multiple regression analyses revealed the independent negative effect of hostility on flow-mediated dilation (FMD). And this association is independent from biomedical risk factors and other psychological factors, specifically anxiety and depression. With respect to Nitroglycerin-induced dilation, none of the psychological risk factors were found to have statistically significant contribution.