BACKGROUND Preoperative radiochemotherapy is widely used in locally advanced rectal cancer. It can improve local control of rectal cancer. However, some researchers believe it increases the incidence of surgical complications. They doubt its safety. Patients with locally advanced rectal cancer receive three different treatments in our hospital, including long-course radiochemotherapy, short-course radiotherapy, and surgery directly. We can compare their differences in postoperative complications. AIM To investigate surgical complications caused by different preoperative radiotherapy regimens. METHODS We retrospectively analyzed 1197 patients admitted between 2008 and 2010 with locally advanced rectal cancer. Three hundred and forty-six patients were treated with preoperative long-course radiochemotherapy (25 x 2 Gy) followed by total mesorectal excision (TME) 6-8 wk later, and 259 patients received short-course radiotherapy (10 x 3 Gy) and subsequently TME 7-10 d later. The remaining 592 patients underwent TME alone without neoadjuvant therapy. According to Clavien-Dindo classification, surgical complications were evaluated for up to 30 d after discharge from hospital. RESULTS There were no deaths in 30 d in all groups after treatment. The major complications were anastomotic leakage and perineal wound complications. The results suggested that both long-course [odds ratio (OR) = 3.624, 95% confidence interval (CI): 1.689-7.775, P = 0.001] and short-course (OR = 5.150, 95%CI: 1.828-14515, P = 0.002) radiotherapy were associated with anastomotic leakage. Temporary ileostomy was a protective factor for anastomotic leakage (OR = 6.211, 95%CI: 2.525-15.385, P < 0.001). The severity of anastomotic leakage did not increase in patients following preoperative radiotherapy (P = 0.411). Compared with THE alone, short-course radiotherapy was associated with an increase in perineal wound complications (OR = 5.565, 95%CI: 2.203-14.057, P < 0.001), but long-course radiotherapy seemed safe regarding this complication (OR = 1.692, 95%CI: 0.651-4.394, P = 0.280). Although the severity of perineal wound complications increased in patients following short-course radiotherapy (P < 0.001), additional intervention was not necessary. CONCLUSION Radiotherapy increased the incidence but not severity of anastomotic leakage. Short-course radiotherapy was also accompanied with perineal wound complications, but intervention appeared unnecessary to ameliorate the complications.