To evaluate the preoperative radiotherapy and its role in anastomotic leakage.A total of 327 patients who had an anterior resection (AR) in elective surgery for a rectal carcinoma were selected and operated in our clinic of surgery during the period from 2003 to 2015. Among them, 135 patients had a low anterior resection (LAR) and the other 192 had an AR. This is a retrospective study. Chi-squared test was used to evaluate statistical differences and the P < 0.05 was considered statistically significant.A total of 126 patients had radiotherapy before surgery, and 50 of them had a LAR. In the other 201 patients, surgery was the first treatment modality, and 83 of them had a LAR. We had an overall anastomotic leakage of 7.95% or 26% patients. Anastomotic leakage was found in 14 patients with LAR, 9 of which had radiotherapy before surgery. From the 12 patients with AR who had an anastomotic leakage, 6 of them had radiotherapy before surgery.Radiotherapy may affect anastomotic healing and increase the risk of leakage. This risk is higher in low anterior anastomoses where a protective stoma may be considered. A better evaluation and support for patients with preoperative radiotherapy is needed in order to diminish the concomitant risk factors as much as possible.