This review describes the many roles of the endothelium in maintaining vessel health.

The endothelium is a barrier that responds to hemodynamic forces and is a source of vasoactive substances.

The endothelium is also a source of pro- and anti-thrombotic and of pro- and anti-inflammatory agents.

Endothelial progenitor cells, endothelial to mesenchymal transition, and the role of miRNAs in endothelial dysfunction are described.

Risk factors for cardiovascular disease are discussed, as well as clinical therapies to prevent/reverse ‘endothelial dysfunction’.