The autism spectrum disorders (ASD) or the pervasive developmental disorders (PDD) are two synonyms of the same group of disorders. They comprise a group of neuropsychiatric disorders characterized by specific delays and deviation in social, communicative, and cognitive development, with an onset starting before 3 years. despite the great array of observations being made at the cellular and molecular dysfunctions associated with autism spectrum disorders, the basic central mechanism of these disorders hasn‘t been proposed in major scientific literature. Multiple etiological factors were discussed including genetic, biochemical, immunological, perinatal, neuroanatomical and psychosocial factors. Glutamate is the principal excitatory neurotransmitters in the mammalian brain. The brain contains abundant glutamate receptors and that destruction of different brain structures could result from excessive stimulation of these receptors leading to many neurodevelopmental or neurodegenerative disorders through a process known by immunoexcitotoxicity. In autism spectrum disorders, immunoexcitotoxicity is accused to be the cause behind the neurodevelopmental changes that occur in autistic patients.