To determine the effect of oral Glutamine powder supplement in reducing radiation/chemoirradiation induced oral mucositis in patients with Head and Neck malignancies Design and Methodology: An open-label single-blind randomized controlled trial was conducted. Arm A - Radiotherapy/Chemoirradiation who were randomized to receive oral Glutamine powder supplement in addition to the regular oral care protocol. Arm B - Radiotherapy/Chemoirradiation who were randomized to receive regular oral care protocol only without Glutamine supplement. Results: Forty-eight patients were accrued in the trial, 24 in the control arm and 24 in the study arm. All patients completed the treatment protocol except 4 patients in a control group who discontinued treatment after 4 to 5 weeks. The number of patients in the control Vs study arm of the Chemoirradiation group was 16 Vs 15 and in Radiotherapy group 8 Vs 9 patients. The occurrence of Grade 3 mucositis was less in the control arm 30% Vs 40% but the onset was later among patients in the study arm (week3). In the Chemoirradiation group requirement for analgesic (92.8% Vs 53.8%), topical anaesthetic(35.7% Vs 7.6% - significant), occurrence of mouth pain(28.5% Vs 15.3%) and Ryles tube feeding (28.5%vs15.3%) were less in the study arm and also tolerated more number of cycles of concurrent chemotherapy (76% Vs 14% p= 0.036). The number of patients having a break in treatment (0% Vs 42.8% -significant) and occurrence of oral thrush (16% Vs 28.5%) was more in the study arm of Radiotherapy only group but the number of patients included was small (6 Vs 7). Nausea and vomiting was the predominant complaint in study arm probably induced by the study mouth wash. The occurrence of dryness of oral mucosa and throat was more in the study arm of the chemoirradiation group but less in radiotherapy only group. Inference: Overall the addition of oral Glutamine powder supplement along with oral care protocol during treatment did not show significant benefit. But there seems to be some benefit with the use of study mouth wash in the chemoirradiation group only. Since the sample size is small will need to do the study with larger numbers to document statistically significant benefit