This study aimed to detect the effect of the dietary addition of quinoa seeds to ameliorate the drastic effects of oxidative stress in Barki male sheep exposed to environmental heat stress. Total of 30 Barki ram lambs were used in the present study. Animals in shaded and unshaded (animals exposed daily to direct solar radiation in the summer) groups were randomly divided into three similsr groups (5 males each). Animals of 1^st group were fed a basal diet without quinoa seeds supplementation, while, those of 2^nd and 3^rd groups were fed diets containing 5 and 10 % quinoa seeds, respectively. Results cleared that the diet contained (10%) quinoa seeds modulated significantly (P<0.05) the increase in the thermo-respiratory responses and the observed anemia, dyslipidemia, and systemic inflammation, including blood leukocytosis, the increase in serum proinflammatory cytokines and heat shock protein-70 concentrations. Furthermore, it improved significantly the gain of body-weight and kidney functions, enhanced the blood antioxidant defense system (total antioxidant capacity, and catalase and superoxide dismutase activities) in the unshaded sheep, and protected them from oxidative stress. In conclusion, feeding on diet containing 10% of quinoa seeds was suitable and safe for sheep nutrition to efficiently alleviate the cruel effects of environmental heat stress in Barki sheep.