Many studies indicated that the CD40/CD40 ligand (CD40L) pathway plays an important role in the pathogenesis of atherosclerosis. It has been demonstrated a protective role of dehydroepiandrosterone (DHEA) against atherosclerosis. The major purpose of our present work was to assess whether DHEA could decrease the expression of CD40 and CD40L on human umbilical vein endothelial cells (HUVECs) induced by interferon gamma (IFN-gamma). We found that DHEA inhibited IFN-gamma-induced expression of CD40 and CD40L in a dose-dependent manner. Moreover, DHEA inhibited IFN-gamma-induced activation of extracellular signal regulated kinase (ERK1/2). The important role of ERK1/2 in DHEA effect was further confirmed by using ERK1/2 inhibitor U0126. These findings suggest that DHEA can inhibit the expression of molecules involved in the inflammatory process in endothelial cells activated with IFN-gamma. Such antagonism is at least partially mediated through the modulation of ERK1/2 pathway. Therefore, DHEA may be considered as a potential preventive intervention for atherosclerosis.