Glutamine is known to be important for cells replicating in culture. It has been proposed that the decrease in plasma glutamine concentration in relation to catabolic conditions, including strenuous exercise, resulting in a lack of glutamine for cells of the immune system, is responsible for the transient postexercise immunosuppression. This review discusses the potential role of glutamine on the postexercise in-vitro changes in immune parameters. Furthermore, the value of glutamine as a nutritional supplement to athletes and the possible influence on these parameters is reviewed.