Purpose The vascular endothelium is an influential contributor to vasodilation at rest, yet its role during peak exercise is relatively unknown. The purpose of this study is to determine if exercise leg blood flow during dynamic submaximal and maximal exercise is related to resting vascular endothelial function. Methods Nineteen subjects (aged 23 ± 0.57 yr) completed multiple assessments of vascular endothelial function including passive leg movement (PLM), rapid onset vasodilation, (ROV) and flow-mediated dilation (FMD). Peak muscle blood flow was assessed during single leg knee extension (KE) exercise. Doppler ultrasound of the femoral artery was utilized to assess muscle blood flow. Results Peak exercise blood flow was linearly related with microvascular endothelial function determined by PLM (P < 0.001) and ROV (P < 0.001). Normalizing muscle blood flow for quadriceps mass did not change this significant association. Individuals with high vascular endothelial function had greater muscle blood flow during KE compared to those with low endothelial function (P = 0.05). Post hoc analysis indicated a significant difference in blood flow between high and low endothelial function groups at 20 W, 30 W, and peak flow (P = 0.042, 0.048, 0.001, respectively). Conclusion Peak muscle blood flow during dynamic exercise is correlated with vascular endothelial function, as measured by PLM and ROV, accounting for between 30 to 50% of the variance in this relationship. These data support the hypothesis that endothelial function significantly contributes to the peak blood flow response during dynamic exercise.