This study investigated whether a single episode of exercise could acutely increase the numbers of endothelial progenitor cells (EPCs) in human subjects. The hypothesis was that exercise may acutely increase either circulating EPCs or cultured/circulating angiogenic cells (CACs). This study shows that exercise can acutely increase EPCs and CACs, and given the ability of these cells to promote angiogenesis and vascular regeneration, the exercise-induced cell mobilization may serve as a physiologic repair or compensation mechanism.