A total of one hundred and twenty, unsexed Sinai Bedouin chicks, one day old were used in this experiment. Chicks were allocated to four dietary treatments of thirty chicks which included three replicates of ten chicks. The experiment lasted for 16 weeks. Growth performance parameters, some blood parameters and economical efficiency were determined. The first group (T₁, control basal diet content normal level of tryptophan supplementation, T_2, T₃ and T₄ contented the supplementation of tryptophan at the levels of 0.20,0.25 and 0.30%, respectively.  Results were indicated that body weight and body weight gain were significantly (P ≤ 0.05) increased by increasing of tryptophan level. The best of feed conversion ratio was recorded for treatment four supplied with 0.30% tryptophan compared with other treatments. Chicks fed diet supplemented with tryptophan were significantly increased in plasma glucose, Total protein and globulin concentration. No significant differences were noted in transaminase enzymes (ALT and AST) plasma blood concentration between all treatments. Significant decrease was observed in plasma total lipids and total cholesterol with adding tryptophan levels (0.20, 0.25 and 0.30%) compared with the basal diets. Tryptophan supplementation at levels (0.20, 0.25 and 0.30%) to chick's diet improved economical efficiency. In conclusion, supplementing tryptophan to Beduin Sinai chick's (during growth period) diet had a positive effect on growth performance and some blood constituents, especially addition 0.30% tryptophan could be recommended for improving Sinai Bedouin chick's health and economic efficiency.