ObjectivesTo investigate the effects of tadalafil on vascular endothelial function and cardiovascular risk in patients with prostatic hyperplasia. MethodsTadalafil 5 mg was given to 20 patients with prostatic hyperplasia for whom an 1-blocker was ineffective. Voiding symptoms and vascular endothelial function were investigated before and after 4 and 12 weeks of administration, using commercial tests for vascular function and vascular endothelial function. ResultsThe participants had a median age of 65 years, a mean body mass index of 24.2 and a mean prostate volume of 36.2 mL measured using transabdominal sonography. Voiding symptoms were significantly improved by tadalafil, based on the International Prostate Symptom Score, quality of life index and overactive bladder symptom score (P < 0.05). There were also significant improvements in vascular function (change of brachial-ankle pulse wave velocity from 1701 [before] to 1657 [4 weeks tadalafil] and 1525 [10 weeks tadalafil] cm/s [P < 0.05]) and vascular endothelial function (change of reactive hyperemia index from 1.36 to 1.56 and 1.89 [P < 0.05]). The change in reactive hyperemia index was significantly correlated with International Prostate Symptom Score, quality of life index and brachial-ankle pulse wave velocity. ConclusionsThe improvement in intrapelvic blood flow by tadalafil can result in improved vascular endothelial function, in addition to improvement of voiding symptoms. The change in reactive hyperemia index seems to correlate with the severity of voiding symptoms, with tadalafil being most effective in patients with mild voiding symptoms.