PURPOSE: This study was designed to investigate the influence of intraoperative and postoperative radiotherapy on functional outcome after rectal resection for rectal cancer. METHODS: One hundred patients who underwent deep or standard anterior resection for rectal cancer were included in this follow-up study. All patients filled out questionnaires regarding morbidity and functional outcome; a subgroup (n = 63) underwent further clinical evaluation. The results were stratified according to radiation: Group I, no radiation (n = 37); Group II, only intraoperative radiation (n = 12); Group III, intraoperative and postoperative radiation (n = 51). RESULTS: Anal continence measured by Kirwan-Parks classification and Wexner score was significantly different within the three groups (P < 0.005, P < 0.0001), whereas continence impairment was least in Group I and greatest in Group III. Patients in Group III demonstrated a significantly worse category in the Kirwan-Parks classification and worse Wexner scores compared with patients in Group I (P < 0.0001). Patients only having undergone intraoperative radiotherapy had a significantly worse continence (Kirwan-Parks classification) than patients without any radiotherapy (P < 0.05). More patients after intraoperative and postoperative radiation therapy complained of fragmented stools (P < 0.05) and urgency (P < 0.05) compared with patients only having undergone surgery; the need to wear pads was higher (P = 0.001). Vector volume manometry revealed better resting sphincter function in Group I compared with Group III (P ≤0.005). CONCLUSIONS: Patients with anterior resection for rectal cancer who undergo full-dose radiotherapy have significantly more impairment of anorectal function than patients without radiotherapy. Patients who were only exposed to intraoperative radiotherapy showed moderate impairment of continence function, suggesting that the influence of radiotherapy on anal function may be dose-dependent and application-dependent. PURPOSE: This study was designed to investigate the influence of intraoperative and postoperative radiotherapy on functional outcome after rectal resection for rectal cancer. METHODS: One hundred patients who underwent deep or standard anterior resection for rectal cancer were included in this follow-up study. All Patients were out of questionnaires regarding morbidity and functional outcome; a subgroup (n = 63) underwent further clinical evaluation. The results were stratified according to radiation: Group I, no radiation (n = 37) RESULTS: Anal continence measured by Kirwan-Parks classification and Wexner score was significantly different within the three groups (P <0.005, P <0.0001), an increase of was continence was was Patients in Group III demonstrated a significantly worse category in the Kirwan-Parks classification and worse Wexner scores compared with patients in Group I (P <0.0001). Patients only having undergone intraoperative radiotherapy had a significantly worse continence (Kirwan-Parks classification) than patients without any radiotherapy (P <0.05). More patients after intraoperative and postoperative radiation therapy compared with patients only having undergone surgery; the need to wear pads was higher (P = 0.001). Vector volume manometry revealed better resting sphincter function in Group I compared with Group III (P ≤ 0.005). CONCLUSIONS: Patients with anterior resection for rectal cancer who did full-dose radiotherapy have significantly more impairment of anorectal function than patients without radiotherapy. Patients who were only exposed to intraoperative radiotherapy showed moderate impairment of continence function, suggesting that the influence of radiotherapy on anal function may be dose-dependent and application-de pendent.