Autism is a disability characterized by impaired social interactions, limited verbal and nonverbal communication, and restricted and repetitive patterns of behavior. Children with autism may not make friends, spend more time alone than with others, and may not develop empathy or other forms of social reciprocity. This study explores the effect of peer- mediated picture exchange communication system intervention in improving vocabulary knowledge in children with autism spectrum disorders. Participants were ten children aged seven, attended a center for children with autism. A pre-post design was used to examine the effect of peer-mediated picture exchange communication system intervention in improving vocabulary knowledge in children with autism spectrum disorders. Findings from this study advocated for the effect of peer-mediated picture exchange communication system intervention in improving vocabulary knowledge in children with autism spectrum disorders.