Increased public awareness of autism spectrum disorders (ASD) and routine screening in primary care have contributed to increased requests for diagnostic ASD evaluations. However, given the scarcity of subspecialty autism diagnostic resources, overreferral of children suspected of having ASD may be contributing to long waiting lists at tertiary care autism centers and delaying diagnosis for those children who truly have ASD. To determine whether children are being excessively referred to ASD-specific diagnostic clinics, our objective was to determine the prevalence of true ASD diagnoses in children referred for diagnostic ASD evaluation. Charts of all patients referred to a regional autism center between April 2011 and August 2012 for suspicion of a possible ASD were retrospectively reviewed and demographic and clinical diagnoses abstracted. Only 214 of 348 patients evaluated (61%) received an ASD diagnosis. Thus, concerns about autism are not confirmed by an ASD diagnosis in a significant number of children.