Glutamine, a non essential branched chain amino acid, is most important non toxic nitrogen carrier in body. It participates in variety of physiological functions. It is a major fuel source of enterocytes and is a substrate for gluconeogenesis in kidney, lymphocytes, and monocytes. It is also a nutrient in muscle protein metabolism in response to infection, inflammation and muscle trauma. The significance of glutamine to metabolic homeostasis becomes evident during periods of stress, when it becomes a conditionally essential amino acid. Role of glutamine as protective agent in hepato-biliary dysfunction, in maintaining mucosal integrity of the Gastrointestinal tract following its administration in patient with major bowel surgery as a supplement and part of TPN in critically ill patients and in patients of septicemia, is well established. However the role of glutamine supplementation in reducing or preventing chemotherapeutic agents induced toxicity in cancer patients is controversial.