Endothelium is the inner most cell layer of blood vessels. Endothelial cells make special barrier that separate blood from extravascular tissues. Intact endothelium regulates vascular tone and permeability and maintains non-inflammatory, anti-thrombotic surface. Through its ability to express pro-coagulants, anticoagulants, vasoconstrictors, vasodilators, cell adhesion molecules, and cytokines, the endothelium has emerged as one of the pivotal regulators of vascular homeostasis. Under physiological conditions, endothelial cell sustains a vasodilatory, anticoagulant, and fibrinolytic state in which coagulation, platelet adhesion, as well as leukocyte activation and inflammation are suppressed. In contrast, during endothelial disturbances, a prothrombotic and pro-inflammatory state of vasoconstriction gets support from the endothelial surface. Release of platelet-activating factor (PAF) and endothelin-1 promotes vasoconstriction, whereas production of von Willebrand factor (vWF), tissue factor (TF), and plasminogen activator inhibitor (PAI)-1 shifts the haemostatic balance towards a procoagulant state. Several factors like infection, hyperglycaemia, hyperlipidaemia, malignancy, oxidative stress, and aging can interfere in endothelial function. It is believed that most of the cardiovascular diseases originate from endothelial dysfunction. Endothelial dysfunction has been shown to be involved in atherosclerosis, thrombosis, hypertension, diabetes, and other cardiovascular diseases. In this review we will specifically highlight the role of endothelial dysfunction in development of cardiovascular diseases.