 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 while the control group will receive placebo during radiotherapy. The severity of oral mucositis WHO grading system, every week, pain status visual analogue scale, every week, quality of life questionnaires before, during and after radiotherapy will also be documented. The differences between the two groups will be analyzed. 