Radical prostatectomy (RP) is one of the curative treatment modalities for localized or locally advanced prostate cancer. Urinary incontinence and erectile dysfunction (ED) are two most common complications after RP. Despite the advancement of prostate cancer treatment, ED post-RP remains a significant morbidity especially for patients who are sexually active pre-operatively. To improve the sexual function post-surgery, numerous strategies have been described including preservation of neurovascular bundles intra-operatively, post-operative physiotherapy, on-demand phosphodiesterase 5-inhibitors (PDE5i), regular PDE5i, intra-carvenosal injection or vacuum suction device. Low-intensity extracorporeal shockwave therapy (LiESWT) is an emerging treatment modality of ED with promising result, and it is a well-established treatment of ED in patients with diabetes mellitus or vasculopathy. Most of the pre-clinical studies were done on post-RP ED rat models with bilateral cavernous nerve crush injury. LiESWT was observed to improve nerve-impaired ED significantly compared to sham procedures. There are currently one pilot study and one randomized controlled trial (RCT) published in the literature on this field. However, the published RCT was an open label study with no sham-controlled arm which could contribute to reporting bias and the treatment intensity might not be adequate. In our proposed study, we make a hypothesis that LiESWT and very early PDE5i can improve erectile function in patients after nerve-sparing radical prostatectomy.