We try to evaluate the effect of sildenafil on nocturnal penile erections of potent men. We recruited 22 potent men (eight medical students and 14 urology residents) 23-29 years old into the study. A disorder-free medical and sexual history and normal erectile functions were the only inclusion criteria. All subjects completed three sessions of consecutive nights using the RigiScan Plus device. After a first night of adaptation, night 2 recordings were their baseline values whereas they received sildenafil 100 mg on night 3. We observed statistically significant improvement with regard to those NPT parameters at the nights with sildenafil: number of erectile episodes; duration of tip rigidity 460%, RAU tip, RAU base and TAU tip (Po0.005). Although the duration of erectile episodes (min) and TAU base were greater during the sildenafil night, these did not reach statistical significance. In conclusion, our study showed that sildenafil can improve nocturnal erectile quality not only in patients with erectile dysfunction as previously published but also in potent males.