Volume 10, Number 1Review ArticlesImpact of Phosphodiesterase Type 5 Inhibitors on Endothelial FunctionTreatment UpdateJohn P MulhallPatrick E TelokenIt is now known that endothelial health is essential for normal erectile function, and changes in endothelial integrity or function may lead to erectile dysfunction (ED). Because phosphodiesterase type 5 (PDE-5) inhibitors have been shown to improve endothelial function, many investigators have questioned whether PDE-5 inhibition will lead to improvement in erectile function. Data from the studies reviewed in this article show that therapy with PDE-5 inhibitors results in improvement in flow-mediated dilation, nocturnal penile tumescence and rigidity, and carotid artery intima-media thickness as well as higher scores on the Sexual Health Inventory for Men, International Index of Erectile Function, Erection Function Domain, and other instruments. Further research is needed to determine whether long-term PDE-5 inhibition can reverse ED and whether use of these agents will decrease cardiovascular morbidity in high-risk populations. [Rev Urol. 2008;10(1):26-30]Erectile dysfunctionTadalafilSildenafilEndothelial functionPhosphodiesterase type 5inhibitors