BACKGROUND: Oxidative stress reflects an imbalance between the reactive oxygen species (ROS) and a biological system's ability to readily detoxify the oxidative agents. Disturbances in the normal redox state of cells can cause toxic effects through production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA. ObjectiveS: The purpose of this study was to evaluate the oxidative status in calves within 3 days of birth. Methods: Twenty calves from Zagros dairy farm were selected. Blood samples were collected from the jugular vein at 0 (before administration of colostrum), 24, 48 and 72 hours after birth for measurement of serum levels of TBARS, Superoxide dismutase and catalase. Results: The results indicated higher levels of serum malondialdehyde concentration at birth that subsequently decreased at 24 and 48 hours after birth (p<0.05). There were lower levels of serum concentration of catalase at birth that followed by increasing in it at 24 and 48 hours after birth (p<0.05). Also, the concentration of superoxide dismutase was lower at the birth that subsequently increased at 24 hours after birth (p<0.05). Conclusions: Based on this study, it seems that antioxidant capacity of calves has been increased within 3 days of birth. Improvement of oxidative status in calves could be due to gradual increasing of their antioxidative capacity and also beneficial effects of colostrum.