OBJECTIVE The present study aims to investigate the radiation-related toxicity and its effects on the quality of life in patients with prostate cancer who received definitive or adjuvant radiotherapy (RT). METHODS Eighty-seven localized prostate cancer patients who underwent RT between January 2011 and June 2016 were enrolled. Each patient filled the EORTC QLQC30 and QLQ-P1225 at four different times (starting and ending at RT, one and six months after RT). EORTC QLQ-C30 questionnaire consists of global health status, five functional (physical, role, cognitive, emotional, social) and nine symptom scales (fatigue nausea/vomiting, pain, dyspnea, insomnia, appetite loss, constipation, diarrhea and financial difficulties). EORTC QLQ-PR25 consists of two functional (sexual activity and sexual functioning) and four symptom scales (urinary, bowel, hormonal treatment-related, incontinence aid). RESULTS According to the EORTC QLQ-C30 questionnaire, global health status score (p=0.007), emotional score (p=0.016), fatigue (p=0.004) and diarrhea score (p=0.003); according to EORTC QLQPR25 questionnaire, urinary score (p=0.024) were significantly poorer at the end of RT. When patients' quality of life questionnaires were compared concerning treatment type (definitive vs. adjuvant RT), RT technique (31) CRT vs. IMRT) and RT field (prostate/prostate+seminal vesicle vs. prostate+ seminal vesicleipelvic lymph node); EORTC QLQ C-30 and EORTC QLQ PR-25 functional and symptom scales were not different between groups. CONCLUSION The RT approach in prostate cancer produced temporary impairment in some scores of QLQ, but all these scores showed improvement from the first month after RT.