This study evaluates the effect of thymol and carvacrol supplementation on meat chemical and microbiological quality of broiler chicken. 120 one day old chicks are purchased and divided into 4 groups treated with different concentrations (4g, 5g, and 6g) of thymol and carvacrol (1:1) for each 20 kg of feed with a control group which has no thymol and carvacrol. At a 42^nd day old, 8 birds collected randomly from each group and cut to breast and thigh muscles for examination their quality chemical and microbiological examinations. The results revealed that total volatile nitrogen (TVN) decreased from (9.07 ± 0.31) mg% in control group till (3.55 ± 0.18) mg% in group C with the highest thymol and carvacrol containing meals in thigh muscle samples. Also, thiobarbituric acid (TBA) decreased from (0.26 ± 0.02)mg/kg in control group to (0.12 ± 0.01)mg/kg in group C with the highest thymol and carvacrol concentration in meals in thigh muscle samples.  Also, total aerobic bacterial count decreased from (9.13×10⁴ ± 2.01×10⁴) cfu/g in control group to (5.02×10³ ± 0.96×10³) cfu/g in C group (6 g of thymol and carvacrol)in thigh muscle samples, total coliforms decreased from (1.17×10⁴ ± 0.20×10⁴) cfu/g in control group to (1.75×10³ ± 0.27×10³) cfu/g in group C , total staphylococcus count also reduced from (7.17×10³ ± 1.63×10³) cfu/g in the control group to (9.18×10² ± 2.01×10²) cfu/g in  group C (6 g)Total fungal count reduced from (1.56×10³ ± 0.21×10³) cfu/g to (5.31×10² ± 0.82×10²) cfu/g in group C. The results revealed the antioxidant and antimicrobial effect of thymol and carvacrol. Also, thymol and carvacrol improved meat quality in the samples.