The effect of glutamine (Gln) on growth performance, intestinal morphology and intestinal barrier function were evaluated in broilers. A total of 320 birds were divided into a control group (CON) and three experimental groups (Gln 1, Gln 2 and Gln 3). Broilers of group CON received basal diet; broilers in group Gln 1, Gln 2 and Gln 3 were supplemented with 0.5%, 1.0% and 1.5 % Gln, respectively, for 42 days. The results indicated that Gln has no influence on the average daily gain (ADG) among the treatments in the periods of 1 to 21 d, 22 to 42 d and 1 to 42 d (P > 0.05). However, Gln improved average daily feed intake (ADFI) and feed intake: average daily gain (F: G), increased the villus height, villus height to crypt depth ratio (V/C) and the activities of sucrose, the ZO1, claudin-1 and occluding mRNA expression levels (P 0.05). Moreover, Gln decreased the crypt depth of jejunum and ileum in broilers at days 21 and 42 (P 0.05). In conclusion, Gln had a positive effect on growth performance and gut parameters by modifying the function of the intestinal mucosa barrier.