This study assessed the effects of using different levels of thyme leaves powder (TLP) supplemented in growing quails birds diets on productive performance, blood indices, carcass characteristics, antioxidant capacity, digestive enzymes, immunity, quality of quail meat and economic efficiency. A total number of 192, unsexed birds (9-day-old) were allocated into four treatments, each treatment contain six replicates of eight birds each. Birds fed a basal diet containing 24% CP with2900 Kcal M.E./ kg diet, a basal diet with 0.5%TLP; a basal diet with 1.0%TLP; a basal  diet with 1.5%TLP; as control group T1, T2, T3 and T4; respectively. Results showed that TLP-diets exhibited significantly improvement in live body weight (LBW), body weight gain (BWG), growth rate (GR) and feed conversion ratio (FCR) values, without a change in feed intake (FI).As well as, there was an increased significantly in digestive enzymes (trypsin, amylase and lipase) and thyroid hormones (T3 and T4) activities, carcass and dressing percentages, antioxidant capacity (T-AOC and GSH-PX) and immune response. The treated groups enhanced the protein profile (T-protein and: Globulin (glob.), with no significant in Albumin (Alb). was found. While, significant decrease was recorded in T- cholesterol (T-chol.), triglycerides (TG) and low-density lipoprotein (LDL) values. Moreover, overall acceptability of quail meat and economic efficiency were improved with TLP diets. In the current study suggests that thyme leaves powder can be used as a feed supplement to improve the growth performance; some carcass traits and blood constituents; enhancing immune-antioxidant status; as well as the highest values of economic efficiency of growing Japanese quail.