Feeding trials were conducted to elucidate the influence of thyme and peppermint oils or their combination on productive performance and some blood biochemical parameters of broiler chickens. A total of 96 day-old boiler chicks (Ross-308) were divided into four treatment groups. The first one was fed the basal diet, while the 2^nd, 3^rd, and 4^th groups were fed the same diet supplemented with thyme oil (100 mg/kg), peppermint oil (100 mg/kg) or a combination of both. Each treatment had three replicates with 8 broilers each. The daily weight gain was significantly (P<0.01) increased while feed conversion ratio and abdominal fat measures were enhanced by the dietary inclusion of the thyme oil and peppermint oil or their combination compared with the control corn-soybean-fed broilers. Interestingly, the addition of thyme oil and peppermint oil or their combination significantly reduced (P<0.01) the total cholesterol and triglycerides levels whereas the other blood profile including total protein, T3 and glucose levels were increased. There were significant variations in carcass characteristics including the percentages of dressed carcass, heart, gizzard, spleen and liver. In conclusion, the of thyme oil and peppermint oil or their combination displayed a greater response as growth promoters compared to the standard diet in order to improve growth performance and decreased cholesterol levels without adverse effect on carcass criteria of broilers.