Autism spectrum disorders is a heterogenous group of neurodevelopmental disorders, the etiology or etiologies of which remain unknown. Increasing evidence of autoimmune phenomena in individuals with autism could represent the presence of altered or inappropriate immune responses in this disorder, and this immune system dysfunction may represent novel targets for treatment. Furthermore, in recent studies, antibodies directed against the fetal brain have been detected in some mothers of children with autism; these antibodies have the ability to alter behavioral outcomes in the offspring of animal models. A better understanding of the involvement of the immune response in early brain development, with respect to autism, may have important therapeutic implications.