Endothelial cells control vascular homeostasis by regulating haemostasis, inflammatory and immune response, vascular tone or angiogenesis. The endothelium is the target of infectious agents capable of altering this equilibrium. Such alterations may result from a direct cytopathic effect with disruption of endothelial integrity, or from an indirect effect due to unregulated activation leading to vascular dysfunction. The endothelium is both the target and the effector of human vascular diseases associated with infection such as atherosclerosis, vasculitis, neuropaludism or graft rejection. A better comprehension of endothelial alterations is these diseases should have biological and therapeutic implications.