Betaine functions as an osmoregulators in the cells and its inclusion can spare the choline, carcass fat reduction. Thus, two hundred eighty eight of seventy eight weeks old laying hens were fed with 0, 500, 1,000, 2,000 ppm betaine addition during the environmentally high temperature stress. Basal diets contained 16% CP and 2,800 ME. Egg production, feed intake, feed conversion were examined for eight weeks. Egg qualities, liver betaine, blood osmolarity, AntiDiuretic Hormone(ADH) were measured at the end experiment. Egg production of hens fed 500, 2,000 ppm dietary betaine and showed significance between control and 2,000 ppm betaine treatment(P<0.05). ADH of blood sera tended to increase as dietary supplemental betaine increased. The results of this experiments indicated that dietary supplemental betaine was able to improve the performance, eggshell breaking strength, liver betaine in this experiment.