To evaluate the degree to which radiation therapy (RT) after prostatectomy for prostate cancer changes measures of urinary quality of life (QOL). Changes in QOL have been well-studied and reported in the setting of definitive RT for prostate cancer. Data on changes in urinary QOL following post-prostatectomy RT are lacking. Patients with prostate cancer receiving post-prostatectomy RT completed the Expanded Prostate Cancer Index Composite (EPIC) survey prior to radiation and at two-year follow-up. We retrospectively evaluated the changes in urinary QOL among 106 patients using the EPIC survey results. The primary outcomes of this study were the EPIC Urinary Summary Domain score and Urinary Subscale scores with subscales of Urinary Function, Bother, Incontinence, and Irritative/Obstructive symptoms. Analysis was also planned for two main sub-groups: those patients receiving RT less than or equal to one year following prostatectomy and those receiving RT more than one year following prostatectomy. The scores were normalized by Likert scale from 0-100 with higher scores representing better reportable QOL. Among the 106 patients analyzed, the mean EPIC Urinary Domain Summary Score worsened at 2-year follow-up after RT, from 77.23 to 72.51 (p=0.0085). Similar worsening was also observed in most EPIC Urinary Domain Subscales including Function (p=0.003), Bother (p=0.0397) and Incontinence (p=0.0003) while the Irritative/Obstructive subscale did not show statistically significant worsening (85.04 to 83.66, p=0.4498). Urinary incontinence showed the greatest observable change among subscales, decreasing by more than 10 points from 66.49 to 56.14 (p=0.0003). Among patients receiving RT more than one year following prostatectomy the EPIC Urinary Summary Domain score worsened from 77.58 to 71.19 (p=0.0031). In contrast, patients treated less than or equal to one year following prostatectomy did not show statistically significant change (76.63 to 74.76, p=0.5888). In related QOL studies, the pre-prostatectomy baseline incontinence domain score is above 90 and post-prostatectomy levels are in the 60’s, which is consistent with the baseline level in our patients. Our results demonstrate that post-prostatectomy RT negatively affects urinary QOL based on the EPIC survey in the post-prostatectomy setting with the greatest magnitude of change reported for urinary incontinence. The decline in incontinence appears to be the primary reason for the decline in the overall score. In perspective, the worsening incontinence domain score after RT is only incremental when compared to the decline seen after prostatectomy. Unexpectedly in our results, patients receiving RT more than one year following prostatectomy showed greater worsening of urinary QOL, which would indicate there is no functional advantage to delaying radiation therapy beyond the initial postoperative period.