Erectile dysfunction (ED) is usually associated with cardiovascular disease and reduced endothelial function. The aim of the present study was to examine the effect of tadalafil and statin on the endothelial function of cavernous and brachial arteries in healthy men and in patients with ED. The cases included in the study were as follows: 150 men with ED complaints for at least 6 months, and 50 healthy volunteers without sexual problems. Patients were randomly divided into four groups of equal numbers. Group 1 received 20 mg of tadalafil on alternate days, Group 2 received 10 mg of statin a day, Group 3 received tadalafil on alternate days and 10 mg of statin a day, and the last group served as controls. Noninvasive evaluation of brachial artery flow-mediated dilatation (FMD) and percentage of increase in cavernosal arteries diameter (PICAD) was conducted via ultrasound at baseline and 4 weeks after administration of tadalafil or atorvastatin. Before drug administration, FMD and PICAD values did not significantly differ among the three treatment groups. After drug administration, FMD and PICAD values significantly increased in patients receiving tadalafil and tadalafil+statin (P < 0.001), but not in patients receiving only statin. These findings suggested that use of tadalafil alone and tadalafil combined with statin improved endothelial function of cavernous and brachial arteries.