EPCs constitute an essential cornerstone in the building and maintenance of the endothelial blood vessels, as well as the functioning of most of the systems of our body, including the endocrine, neurological, hematological, immune and inflammatory systems as well as organs such as kidney, heart, lungs and brain. Moreover, they serve as gatekeepers, preventing degenerative processes that affect every organ and tissue. It is important to know and understand that medications and hormones have an effect on these cells. This knowledge may help us to stimulate and maintain EPCs as well as plan future pharmacological interventions.