Exposure of animals to ambient temperature above the thermo neutral zone caused heat stress. Alterations in digestion and absorption of nutrients as well as damage to the small intestine epithelia associated with the production of reactive oxygen species (ROS) may occur in heat stress pigs, resulting in depressed performance. The cells possess an antioxidant system capable of protecting the animals against the effect of heat stress. However, when ambient temperature increases beyond the thermo neutral zone, ROS production also increases provoking an imbalance between ROS and antioxidant production. This review provides relevant information related to the alterations that occur at intestinal, cellular and molecular level in animals exposed to heat stress, and the effect that methionine and arginine as antioxidant amino acids, and their use in diets for heat stress pigs.