The exact origin and functional definition of endothelial progenitor cells (EPCs) remains rather controversial, but many authors agree that the main feature of EPCs is the ability to directly participate in vessel growth by differentiation into endothelial cells in vivo. The majority of these cells originate from the hematopoietic stem cells of the bone marrow and, under specific signals, differentiate and shift into the systemic circulation, contributing to the neoangiogenic process and repair of the damaged endothelial monolayer. Recently, it has been demonstrated that the number and function of EPCs is positively linked with an improved endothelial function or regeneration but inversely correlated with cardiovascular risk factors: a reduced number of EPCs is an independent predictor of morbidity and mortality of cardiovascular diseases and of atherosclerotic disease progression. Owing to their role in endogenous maintenance and repair of damaged endothelium, EPCs have been examined for therapeutic potential in ischemic diseases and there are evidence-based perspectives regarding their use for vascular regenerative medicine.