Because erectile dysfunction (ED) and cardiovascular disease share a number of risk factors, it is important to understand the haemodynamic and cardiovascular effects of treatments for ED, including the phosphodiesterase (PDE) type 5 inhibitors. In healthy subjects, administration of tadalafil (a potent and selective inhibitor of PDE5 indicated for the treatment of ED) resulted in small decreases in standing blood pressure. In the general population of men with ED, the effects of tadalafil on haemodynamic parameters were similar to those observed with placebo. As with sildenafil, administration of tadalafil with any nitrate is contraindicated. Tadalafil administration was not associated with prolongation in QT interval. Safety data show that the incidence rate of myocardial infarction following treatment with tadalafil was comparable to that observed in the age-standardized male population, and incidence rates of cardiovascular events observed in patients who were and were not treated with concomitant antihypertensive therapy were comparable. These results demonstrate that tadalafil has no clinically relevant effects on haemodynamics, although it should not be used in combination with nitrates. In addition, integrated analyses of the cardiovascular adverse events in the phase III safety database as a whole, and in patients taking concomitant antihypertensive medication, demonstrate that tadalafil is not associated with increased risk for clinically significant cardiovascular events.