We retrospectively analyzed the effects on the erectile function (EF) of no treatment (NT), and an oral therapy (OT; on-demand therapy (OD) or a regimented rehabilitation (RR) program with phosphodiesterase type 5 inhibitors (PDE5-Is)), in a cohort of 196 consecutive patients following nerve-sparing radical retropubic prostatectomy (NSRRP). Patients undergoing bilateral NSRRP (BP; n = 147) and unilateral NSRRP (UP; n = 49), chose between OT (PDE5-Is OD or RR program) and NT. Patients who chose OD therapy received PDE5-Is (100mg sildenafil, 20 mg tadalafil and vardenafil), whereas patients who chose the RR program received 100mg sildenafil or 20 mg vardenafil three times a week, or 20 mg tadalafil twice a week at bedtime. The t-test for unpaired data and Fisher test were used for univariate analyses, logistic regression multivariate analysis was used to test the accuracy of available variables to predict EF recovery after radical prostatectomy. Potency rates were significantly correlated with the surgical technique and with OT when compared to NT (P<0.02), respectively 68.7% for BP (61% with no therapy and 71% with PDE5-Is) and 44% for UP (29% with no therapy and 51% with PDE5-Is), while no statistically significative differences were found between OD and rehabilitation protocols (72% with rehabilitation and 70% with OD therapy in BP, 52% with rehabilitation and 50% with OD therapy in UP; P = NS). Early OT with PDE5-Is (OD or RR program) was superior to NT in recovery of EF in NSRRP. Furthermore, an RR program with PDE5-Is did not appear to be superior to OD therapy.