Abstract: One hundred and fifty days old of unsexed broiler chicks were reared on floor pens and distributed into 5 dietary treatments (starter = 0-21 days old and grower = 22-35 days old) including 4 sources of growth promoters (GP’s) represented two sources of essential oils, synbiotic preparation (Amio-Flash®) and phytobiotic preparation (Bio-Strong®). The experimental diets were Con. = unsupplemented basal diet, Tgro = Con.+Geranium oil, Ttno = Con. +tangerine oil, Tamf = Con. +Amio-Flash® and Tbis = Con. +Bio-Strong®. Experimental results showed that Body Weight Gain (BWG) was significantly improved and Feed Intake (FI) increased by dietary GP’s inclusion only at starter period but not significantly affected during growing and overall period for both traits. Geranium oil supplementation caused a significant higher FI during grower and overall periods. Although, GP’s supplementation didn’t significantly affect Feed Conversion Ratio (FCR) but both Con. and Tamf recorded the best FCR at all experimental periods. The amio-flash (as synbiotic) was the most effective growth promoters between tested ones for improving FCR and BWG. Neither supplementation of diets with GP’s nor GP’s source significantly affect carcass trait percents or most plasma components except globulin and A/G ratio, which were affect by GP’s supplementation. Tangerine oil and Bio-Strong favorably increased total protein and decrease A/G ratio of broiler plasma. Besides, the higher value of plasma ALT for Bio-Strong and AST for both geranium oil and Bio-Strong suggests that both GP’s may have a negative effect on liver function of broiler chicks.