An experiment was conducted to compare the effect of supplementing multi-enzyme preparation Phytabex-Plus (200 g/ ton), or some biological growth promoters [Amio-Flash (2 Kg/ ton) and Bio-Strong (150 g/ ton)] or new natural growth promoter [Bio-Feed (1 Kg/ ton)] to starter and grower diets on growth performance, carcass traits and some blood plasma constituents as well as economic efficiency during growth period (0-5 wks of age). A total of 150 unsexed one day-old Cobb broiler chicks were distributed equally into 5 dietary treatments in 3 replicates of 10 birds each. Feed and water were supplied ad-libitum till the end of the experiment at 5 weeks. At the end of experiment, 3 birds from each treatment were randomly slaughtered for blood plasma constituents analysis and carcass measurements. The results indicated that live body weight, body weight gain, feed consumption, feed conversion ratio and performance index were significantly affected by growth promoters or enzyme preparation supplementation during the overall experimental period (0-5 wks of age). Chicks fed diets supplemented with Amio-Flash recorded the best values of the previous traits than those fed other dietary treatments. Carcass traits indicated that different growth promoters or enzyme preparation had no effects on carcass characteristics. Plasma total protein, Albumin, globulin and cholesterol were significantly increased while,, AST and ALT were significantly decreased by adding Amio-Flash to the diets as compared to the control. Feeding economical efficiency was improved for broiler chicks by feeding diets supplemented with Amio-Flash or enzyme preparation than the control. These results indicated that supplementing Amio-Flash as a growth promoter or Phytabex-Plus as an enzyme product to broiler diets could be used to maximize growth performance as well as economic efficiency during growth period (0-5 wks of age).