ASD develops through a complex set of etiologies that involve environmental, genetic and immunological factors. Objective: The subjectivity of behavioral diagnosis urges the need for biomarker clinical tests to improve and complement ASD diagnosis. Methods and results: A wide range of biomarkers to diagnose and indicate the severity of ASD include metabolic and genetic biomarkers. The role of oxidative stress in the etiology of an ASD diagnosis, including increased lipid peroxidation, altered antioxidant enzymes in plasma, nutritional and genetic factors; as tracking biomarkers will be discussed. Conclusion: We will comprehensively review the biomarkers reported in ASD in addition to our own 20 years’ experience in Egypt. It is important to establish those biomarkers resulting able to help diagnosis and optimize the treatment of ASD.