Aim: To analyze the treatment outcomes, patterns of failures and prognostic factors for patients with anal cancer treated with radiotherapy (RT). Materials and Methods: Between January 2000 and December 2015, 83 patients with anal squamous cell carcinoma were treated with definitive RT. The median RT dose applied to the primary carcinoma site was 55 (range=45-64) Gy. Seventy-six patients (91.6%) received concurrent chemotherapy, and the most common regimen was 5-fluorouracil plus mitomycin C. Results: The median age of patients was 64 (range=36-86) years, and there were 21 males and 62 females. The overall complete remission rate was 89.2%. The median duration of follow-up was 51 (range=3-173) months. The actuarial 5-year overall, progression-free survival (PFS), locoregional progression-free, and distant metastasis-free survival rates were 85.0%, 70.4%, 78.2%, and 82.6%, respectively. On multivariate analysis, eventual treatment response was the only prognostic factor for overall (p=0.023) and progression-free (p〈0.001) survival. Age (p=0.013) and eventual treatment response (p〈0.001) were significantly associated with locoregional progression-free survival. Initial treatment response, lymph node involvement and RT technique significantly affected distant metastasis-free survival (p=0.016, 0.048 and 0.002, respectively). Conclusion: RT, mainly with concurrent chemotherapy, showed acceptable treatment outcomes and safe toxicity profiles.