Heat stress (HS) is one of the most stressful factors affecting on animal health, production, and product quality. Ruminants are prone to heat stress due to their rapid metabolic rate rapid growth, high level of production, and species-specific traits such as rumen fermentation, sweating impairment, and skin insulation. HS can lead to oxidative stress that occur when the internal antioxidant mechanisms cannot neutralize an increase in the production of reactive oxygen species (ROS). The present study was established for discussing the effect of heat stress on some physiological and biochemical parameters in calves followed by treatment trials by adding Rosemary and vitamins in their ration. Currently, 90 female calves were used for this study. Animals were divided into 9 groups which exposed to 3 different levels of temperatures at (30-35^oc, 36-40^oc and 41-45^oc) and 3 different types of nutritional supplement (NRC ration, NRC + Vit E& C and NRC + Rosemary). According to the findings, there was a significant increase in the respiratory rate, heart rate and the rectal temperature in heat stressed calves. Also, there was a significant increase in MDA, cortisol, haptoglobin, liver enzymes and renal function tests in blood of these calves. By contrast, the results showed a significant decrease in the level of antioxidants, glucose, and insulin in heat stressed calves when compared with the control. By Adding Rosemary, and Vitamin (E&C) in the ration of heat stressed calves, the result showed a significant improvement in the measured parameters of these heat stressed calves.