Abstract Background: Autism spectrum disorder (ASD) is a wide-spread neurodevelopmental syndrome which is characterised by communication difficulty. It has steadily increased in prevalence, becoming the most prevalent disorder among psychiatric disabilities. In addition, Vitamin A has a very crucial role in nervous system and brain development. There-fore, Vitamin A deficiency (VAD) can have a tremendous effect on children neurodevelopment and ASD development as a consequence. Aim of Study: To assess the Vitamin A level in the Egyptian ASD children before and after Vitamin A supplementation; as well as its association with ASD symptoms. Material and Methods: This is a two-stage study which the first stage is controlled cross-sectional study, while the second stage is interventional study, clinical trial, open label. We included Children with ASD diagnosed by (DSM-V) criteria, as well as healthy controls. Results: We observed that 33.3% of ASD patients had a family history of similar cases. In addition, we observed a statistical decrease of Vitamin A level in the study group compared to the control group. ASD patients with low Vitamin A level had a mean and SD of 51.27±25. This was increased significantly after Vitamin A supplementation to be 81.18±  21.652. Conclusion and Implications: However, Vitamin A defi-ciency is popular in the developing countries including Egypt, yet ASD children had lower Vitamin A levels than normal children. In addition, Vitamin A supplementation seemed to significantly improve autistic symptoms of our patients.