DSM-IV criteria for autistic and Asperger's disorders were applied to 157 children with clinical diagnoses of autism or Asperger's disorder. All children met the DSM-IV criteria for autistic disorder and none met criteria for Asperger's disorder, including those with normal intelligence and absence of early speech delay. The reason for this was that all children had social impairment and restricted and repetitive behavior and interests (required DSM-IV symptoms for both autistic and Asperger's disorders) and all had a DSM-IV communication impairment (which then qualified them for a diagnosis of autistic disorder and not Asperger's disorder). Communication problems exhibited by all children were impaired conversational speech or repetitive, stereotyped, or idiosyncratic speech (or both), which are DSM-IV criteria for autism. These findings are consistent with those of 5 other studies and indicate that a DSM-IV diagnosis of Asperger's disorder is unlikely or impossible.