Background: Post-operative urinary retention (POUR) after a rectal surgery for cancer is relatively frequent. This study aims to identify risk factors of POUR in patients who underwent anterior resection of the rectum for rectal cancer. Methods: This study is a retrospective single- center study on a population of 238 patients who underwent rectal surgery for cancer and were treated as part of an Enhanced Recovery After Surgery (ERAS) program between July 2011 and October 2020 at the University Hospital of Lausanne (CHUV). The diagnosis of urinary retention was based on the inability to urinate spontaneously requiring the placement of a urinary catheter. Patients were divided into 2 groups, one with urinary retention versus one without urinary retention. After statistical analysis, a p-value lower than 0.05 was used to indicate statistical evidence. Results: A total of 238 patients (139 men (58%) and 99 women (42%)) were included. 6.7% of the patients had urinary retention. The statistically significant risk factors demonstrated in this study were older age (p value = 0.012), history of benign prostatic hyperplasia (p < 0.01) and large prostate volume (p value = 0.03). Conclusion: Age, history of benign prostatic hyperplasia and large volume may be risk factors for POUR after a rectal surgery. We advise close monitoring of bladder emptying in these groups of patients in order to decrease post-operative morbidity. These findings need confirmation by well-designed prospective studies.