INTRODUCTION AND OBJECTIVE: Colorectal cancer (CRC) is one of the most common malignant tumors in the world, being the second leading cause of cancer deaths. Several treatment modalities are used for CRC patients, and radiotherapy has shown a reduction in local tumor recurrence rates, improving survival. Thus, this study aimed to investigate the role of radiotherapy in the treatment and prognosis of colorectal cancer. MATERIAL AND METHOD: This is a cross-sectional observational study in which data were obtained from medical records of a reference hospital in the treatment of cancer in the Midwest of Brazil. Medical information was collected from 151 individuals diagnosed with CRC, who underwent radiotherapy, chemotherapy and / or surgical treatment. Clinical stage of the tumors was evaluated for all patients. For statistical analysis, IBM SPSS Statistics v.20 program was used, using Chi-Square Test or Fisher's exact test, odds ratio and 95% confidence interval (CI), considering a p≤ 0.05 significant. RESULTS: From 151 individuals included in the study, 39 (25.8%) were treated by combining chemotherapy, radiation therapy and surgery. Most individuals were female and the average age was 60 years. All patients treated with radiotherapy were also submitted to chemotherapy. Radiotherapy was the treatment of choice for individuals who had tumor lesions in the rectum (83.7%) (p = 0.000; OR 0.14; 95% CI 0.06-0.34). CONCLUSION: Radiotherapy was the treatment of election for rectal tumors, and the combination radiotherapy and chemotherapy seems to potentially decrease the primary tumor volume, when compared to its isolated use. There are still controversies about the use of radiotherapy in CRC, especially for tumors in early stages. More research needs to be carried out to clarify the role of this therapy in the prognosis of CRC.