This study was conducted to investigate the effects of dietary glutamine (Gln) on the productive performance and egg quality of laying hens. A total of four hundred Lingnan Yellow laying hens aged 34 weeks were randomly assigned into four groups (100 laying hens/group), and fed, respectively, with diets supplemented with 0% (control group), 0.2%, 0.4%, and 0.8% Gln during the 6-week feeding period. The results were as follows. First, the productivity of laying hens fed with 0.8% Gln in diet was significantly increased (p<0.05); however, the egg quality (egg weight, yolk weight, shell weight, egg shape index, shell thickness, shell density, shell breaking strength, yolk color, yolk index, and Haugh unit) was not affected compared with that of the control group (p>0.05). Second, luteinizing hormone (LH) (p<0.01), follicle stimulating hormone (FSH) (p<0.01), triiodothyronine ($T_3$), and tetraiodothyronine ($T_4$) contents (p<0.05) in blood of laying hens fed with 0.8% Gln in diets were also significantly improved, and greater improvement in the duodenum and oviduct structure was observed in that treatment group. This study indicated for the first time that diets with 0.8% Gln were able to increase the productive performance of laying hens through stimulating hormone secretion and better development of both the duodenum and oviduct structure in laying hens.