OBJECTIVE Autism a childhood neurodevelopmental disorder, with onset prior to 36 months old. The etiology of autism is complex, and usually, the underlying pathologic mechanisms are unknown. Recently, alteration in heavy metals and trace elements had some interest. The aim of the present study is to examine levels of trace elements and heavy metals in hair samples, of autism spectrum disorders in the Riyadh area. METHODS The study was conducted in Riyadh area, Kingdom of Saudi Arabia between September 2003 and April 2004. Seventy-seven autistic children participated in the study, all with confirmed diagnosis according to E-2 diagnostic criteria for autistic spectrum disorders. Hair samples were analyzed by atomic absorption spectrophotometer. The measurements of 9 heavy metals (lead, mercury, aluminum, arsenic, barium, cadmium, nickel, antimony and strontium), and 11 trace elements (sodium, calcium, chromium, copper, iron, magnesium, manganese, zinc, cobalt, selenium and molybdenum) was carried out. RESULTS The current study showed significantly higher levels of toxic heavy metals mercury, lead, arsenic, antimony and cadmium in autistic spectrum disorders as compared to the control children. Moreover, hair samples from children with autistic spectrum disorders contained significantly lower concentrations of calcium, copper, chromium, manganese, iron and cobalt, as compared to normal children. In addition, we found a significantly higher incidence of social withdrawal, sleeping and eating disorders, speech and language disorders among autism spectrum disorders as compared to controls. CONCLUSIONS The present study demonstrated alteration in levels of toxic heavy metals and essential trace elements in children with autistic spectrum disorders as compared to normal children. This suggests a possible pathophysiological role of heavy metals and trace elements in the genesis of symptoms of autism spectrum disorders, such as social withdrawal, eating and sleeping disorders. In turn, those children with autistic spectrum disorders might benefit from chelating therapy for heavy metal poisoning and supplementation of essential trace elements.