Gap junctions (GJs) are comprised of members of the connexin (Cx) family and endothelial GJs play an important role in vascular function, stability, and homeostasis. Endothelial cells (ECs) communicate to adjacent ECs, vascular smooth muscle cells, leukocytes and platelets via GJ, thereby Cx–mediated interactions with each type of cells have shown different effects over a wide range of vascular functions. Endothelium regulates vascular inflammation, blood coagulation, vasodilation/ vasoconstriction, angiogenesis, and vascular stiffness. Endothelial dysfunction is related to cardiovascular diseases such as atherosclerosis. The alteration of Cxs expression in vascular component cells contributes to the development of endothelial dysfunction and cardiovascular diseases. We have summarized here the role of GJs in the function of the vascular endothelium.