This study was conducted to demonstrate the effect of supplemented thyme powder on growth performance, blood parameters and carcass traits in Japanese quail. One hundred and eighty (180) quail chicks after one week rearing were divide into four treatments which called: (T1) basal diet without thyme ; (T2) basal diet added 0.5% of thyme powder; (T3) basal diet added 0.75% of thyme powder; (T4) basal diet added 1% of thyme powder. Each treatment included 45 birds with three replicates, 15 birds in each replicate. all treatments were fed ad libitum of their own diet. The results showed that the addition of thyme powder significantly (p≤0.05) increased the values of live body weight and body weight gain. The food consumed did not differ significantly in all treatments (p≤0.05). Male eviscerated dressing percentage did not differ significantly (p≤0.05), however, there is a significant increase (p≤0.05) in females. The breast, wings, legs and backs percentage increased significantly (p≤0.05) in both of males and females of the thyme supplemented treatments. Blood serum levels of cholesterol, triglycerides in males and females decreased significantly (p≤0.05) of the thyme added treatments. HDL increased significantly (p≤0.05) in both of males and females. LDL in males and females decreased significantly (p≤0.05). In conclusion, 1% of thyme powder supplemented to dietary can be used as an effective diet supplement to enhance growth performance, carcass characteristics and blood lipids in Japanese quail.