To study prevalence rates of pervasive developmental disorder (PDD) symptoms and differences between subtypes in school age Iranian children. A random sample of 2,000 school age children from both genders was selected. A parent-completed, DSM-IV-referenced rating scale of PDD symptoms was used. About 1.9% of the sample obtained screening cutoff scores for probable autistic disorder and 0.5 for probable asperger's disorder. The rate of probable PDD was not more in girls than the boys. The rate of suspected cases of PDD in Iran is very high and probable autistic disorder is not gender related. It shows the need for more consideration of PDD in the mental health programs planning.