Introduction: The role of vitamin D in prevention of many diseases have been confirmed by many studies recently. The aim of this study was to determine the levels of oxidative and anti-oxidative markers after administration of vitamin D in asthmatic children. Methods: This randomized clinical trial study has been done on 60 asthmatic children who randomly divided into two groups. One group group received a single dose of vitamin D (5000 ng/ml) and another group received placebo with the same dose in the form of prescribed vitamin D. The levels of 25 (OH) D were measured at the baseline and also levels of vitamin D, glutathione peroxidase 1 (GPx1) and Total Oxidative Capacity (TOC) were measured 10 days after prescription single dose of vitamin D. Results: The amount of Vitamin D at baseline in two drug and placebo groups were similar but at the end of 10 days in the drug group with 54.8±20.92 significantly higher than placebo group with 30.73±12.98. The GPx1 levels at the end of 10 days in the drug group with 44.2±30.9 significantly more than placebo group with 29.5±12.9. Overall TOC amount at the end of 10 days in the drug group with 15.29±3.38 IU was similar to placebo group with 15.06±3.53 IU. The levels of vitamin D in rural children was significantly more than urban children. Conclusion: The results showed that, vitamin D could significantly increase the amount of GPx1, hence it can be used as an appropriate drug in the treatment of asthmatic children.