The objective of this study was to determine the effects of dietary supplementation with different betaine , choline and methionine levels on productive performance, egg quality and some blood parameters of laying hens under high ambient temperature.  Two hundred and  thirty one birds (210 pullts +21cocks ) at 24 weeks -old  from Inshas developed strain were divided into seven groups of 30 pullets in three replicats ( 10 pulles and one cock ). The frist group was fed the basal diet without supplementation (control 0 % ) ,the second and the third groups were fed the same diet with betaine (0.1 and 0.2 % ,respectively). Choline and methionine were also supplemented at 0.2 % and 0.4 % for choline and 0.1 % and 0.2%  for methionine in group 4 to 7 . Birds of each group were housed in open floor pen . Results showed that ,body weight  change (g/day) increased and feed conversion ( g feed / g egg)  improved significantly by dietary supplementation of methionine  (0.2% ) during the period from 24 to 36 wks of age .  Rectal temperature and respiratory rate  were decreased significantly with supplementation of betaine ( 0.1%)  and  methionine (0.1%)   in diet as compared to control group, and no significant effect on egg quality traits except egg  weight . It is concluded that supplemental dietary betaine, choline and mithionine enhanced growth performance and reduced respiration rate and rectal temperature and improved some blood parameters  forInshas strain subjected to heat stress.