Abstract: Dietary manipulation of heat induced oxidative stress is one of the most widely used method to alleviate the negative effect of heat stress. The combination of two or more potential antioxidants are known to protect against heat stress. Therefore, 200 day old broiler chicks were raised under hot climate to determine the effect of ascorbic acid and zinc bacitracin and their combination as antioxidants. Birds were divided into four treatments; the first treatment (T1), the control was provided with basal diet. Second (T2) and third (T3) treatments were provided with 1 g ascorbic acid and 100 mg zinc bacitracin per kg basal diet, respectively. The fourth treatment (T4) was provided with a combination of T2 and T3 for 42 days. Performance parameters were reported every fortnight. Blood samples were collected every fortnight and the harvested sera were used to determine oxidative stress biomarkers. Ascorbic acid and zinc bacitracin were safe for heat stressed birds since the liver and kidney function indicators were not changed. Ascorbic acid and zinc bacitracin lowered lipid peroxidation level (Malondialdehyde; MDA) and increased the activity of catalase (CAT), glutathione-S-transferase (GST) and Super Oxide Dismutase (SOD) whereas, glutathione peroxidase (GPx) activity remained unchanged in all treatments. Serum ascorbic acid concentration was significantly (p<0.05) increased accompanied with hypocholesterolemia in heat stressed broilers receiving ascorbic acid compared to the control. Performance parameters were not influenced by feed additives. In conclusion, ascorbic acid was more potent than zinc bacitracin and their combination in increasing the level of enzymatic and non enzymatic antioxidants.