Objective: Autism Spectrum Disorder (ASD) is a common neurodevelopmental disorder whose cause remains unknown. Oxidative stress is one of the possible causes of many disorders, including neurological ones. This study aims to measure some oxidative stress biomarkers (Malondialdehyde “MDA,” Advanced Oxidation Protein Product “AOPP,” Glutathione “GSH”) within Syrian children with ASD. Methods: MDA, AOPP & GSH were measured in the plasma of a total of 60 children. The ages of the children ranged from 1 to 13 years old. Thirty children had ASD and were compared with 30 controls that don’t have ASD. Fifteen of the controls were siblings of an ASD child, while the remaining 15 had no relations with ASD. Results: MDA and AOPP plasma levels were higher in ASD children compared with non-related controls ( P = .0001). However, there were no significant differences between MDA and AOPP plasma levels in ASD children in comparison with related controls ( P > .05). Alternatively, GSH plasma levels were lower in ASD children compared with both related and non-related controls ( P = .0001). Conclusion: Further studies are needed to investigate more regarding the diagnostic use of oxidative stress biomarkers, and the therapeutic use of antioxidants in children affected with the autism spectrum disorder.