Introduction: Patients diagnosed with head and neck cancer are given radiation therapy for its treatment. Radiation therapy causes side effects which patient experiences while receiving it. The purpose ofthe study was to assess symptoms of side effects of radiation therapy in patients receiving radiotherapy. Methodology: Quantitative research approach and descriptive research design was adopted in this study. Purposive sampling method was used to select 46 patients who were diagnosed with cancer of head and neck and were scheduled to receive radiation therapy. Data were collected by interview method using EORTC QLQ H&N 35 questionnaire. Onthe first day of radiotherapy baseline assessment, on 10th day of radiotherapy 1st assessment of symptoms related to radiation therapy’s side effects and on 21st day of radiotherapy 2nd assessment of symptoms caused by side effects of radiation therapy was done. Results: results revealed a gradual increase in the symptoms of side effects of radiation therapy such as difficulty in swallowing,dryness of mouth, pain etc. Conclusion: It is concluded that patients having head and neck cancer experience side effects of radiotherapy as radiotherapy progresses.