Approximately 50% of prostate cancer patients receiving radiotherapy develop erectile dysfunction within 3-5 years. The precise role of radiation-induced neurogenic injury post-radiotherapy has not been fully established. The CNs are post-ganglionic parasympathetic nerves that assist in the penile erection, located beside the prostate. Male rats were exposed to RT, and erectile function, CN injury, and penile tissue damage were evaluated. Physiological, electrophysiological, and TEM analysis elucidated the extent of damage to CN. RT also significantly increased the mRNA and protein expression of neural damage markers in the MPG. A significant upregulation of both RhoA/ROCK1 mRNA and ROCK1 protein expression were observed in radiated MPG. This result will introduce a rationale for utilizing novel strategies to prevent CN damage post-RT, and the RhoA/ROCK signaling pathway could be a feasible future target pathway to mitigate RiED in prostate cancer patients.