Autism Spectrum Disorder (ASD) is characterized by the impairment of communication and social interaction and by repetitive, restricted and stereotyped interests. ASD is often accompanied by comorbidities; eating disorders are frequent and imply important nutritional deficits (i.e. deficiencies of vitamins, minerals and fatty acids). Vitamin D has a critical role in neurodevelopment and serum levels in ASD are reported inadequate. A useful reference for setting up a correct diet in childhood is the food pyramid, which is inspired by the Mediterranean Diet (MD). The MD guarantees an intake of nutrients, considered optimal to maintain an adequate nutritional status. The aim of this study is to explore serum levels of Vitamin D and food habits (through MD adherence) in a sample of children with ASD and evaluate a possible correlation between these factors.