According to the MassachusettsMale Aging Study (MMAS), the

estimated prevalence of erectile dys-function (ED) of any degree in men 40 to 70 years of age is 52%, with 25 % having moderate dysfunction and almost 10% of this age group unable to achieve erec-tions at all.1, 2 Data from a wide range of clinical trials demonstrate that the oral phosphodiesterase type 5 (PDE5) inhibitors offer efficacy in the treatment of this disorder. Further, as each of these agents—shorter-acting sildenafil citrate and vardenafil hydrochloride, and longer-acting tadalafil—was developed, it proved to confer benefits over placebo in healthy men, in men with comor-bidities such as diabetes and cardiovas-cular disease (CVD), and in men with surgically induced ED. All the PDE5 inhibitors are generally safe and well tolerated, a finding that greatly enhances any and all efficacy benefits. Sildenafil, the first of these agents, offered early onset of action, a favorable side effect profile, efficacy in men with diabetes, and the return, in some men, of spontaneous erections after nerve-sparing retropubic radical prostatectomy (NSRRP); the development of vardenafil brought these features plus efficacy in men previously nonresponsive to silde-nafil. Tadalafil, with its extended duration of activity, then built on the established foundation of benefits by expanding the window of time in which couples could attempt and complete successful inter-course