Purpose: The purpose of this study was to identify predictors and treatment outcome of late bowel toxicity after three dimensional pelvic radiotherapy for genitourinary malignancies and also to describe our experience with Argon Plasma Coagulation (APC) in this toxicity.Patients and methods: Between March 2004 and March 2010, all patients who had completed a course of pelvic radiotherapy for genitourinary malignancies at our Institute were enrolled in this study. Every patient with lower GI symptoms underwent sigmoidoscopy and accordingly, some patients were subjected to intervention by APC.Results: One hundred and thirty-six patients met all inclusion criteria. Median FU period was 37 months. Chronic diarrhoea was scored as Grade 1 or 2 in 35 patients (25.7%). Chronic proctitis was scored as Grade 1 or 2 in 17 patients (12.5%) and Grade 3 in 6 patients (4.4%), 25 patients developed chronic bleeding per rectum, 16 (11.8%) were Grade 1 or 2, while 9 patients (6.6%) were Grade 3. Both maximum rectal dose and comorbidity ≥1 significantly correlated with the development of chronic proctitis (p = 0.040 for both).Endoscopic findings showed mucosal injury in 59 cases (84.29%) and vascular injury in 42 patients (60%). APC was successful in controlling bleeding and other symptoms in 14 cases (82.4%) and 16 cases (70%) respectively.Conclusion: Three dimensional pelvic radiotherapy using two-phase technique is associated with a low level of Grade 3 late lower gastrointestinal toxicities. The most common presenting symptom is chronic diarrhoea. Both maximum rectal dose and comorbidity ≥1 significantly predict the development of chronic proctitis. APC is an effective, safe and well-tolerated treatment for chronic radiation proctitis.