Supplementation with glutamine(Gln) has beneficial effects on intestinal and immune functions. Cage-reared chicks suffer from various stressors during early growth, but the effect of Gln supplementation on growth performance and stress hormones is uncertain. We investigated the effect of Gln on growth performance and blood corticosterone levels in Hyline chicks. Groups of 3-day-old chicks were fed one of three diets: normal feed(CTL group), normal feed supplemented with a low level of Gln, or normal feed supplemented with a high level of Gln. Growth and various physiological and biochemical parameters related to stress were assessed. On day 30, after a 24-h fast, blood was analyzed for corticosterone and other parameters, including glutamic oxaloacetic transaminase, gamma-glutamyl transpeptidase, total bilirubin, lactate dehydrogenase, total cholesterol, high-density lipoprotein cholesterol, blood urea nitrogen, blood total protein, and inorganic phosphate. Growth performance was maintained in Gln supplemented groups. The corticosterone level was decreased in the two groups receiving Gln supplementation compared to the CTL, and all other humoral factors did not differ between the groups. We suggest that Gln supplementation is a safe and useful strategy for reducing the effects of stress in cage-reared chicks.