 This study will enroll 60 consecutive patients who are scheduled to receive radiotherapy withwithout chemotherapy due to head and neck cancers. Basic data will be recorded along with tumor related variables. Then they will be divided randomly into study group and control group. The study group will receive oral glutamine during radiotherapy while the control group will receive placebo during radiotherapy. The severity of oral mucositis WHO grading system, pain status visual analogue scale, quality of life questionnaires will also be documented. The differences between the two groups will be analyzed. 