In 1944, Asperger described a syndrome that was subsequently given his name, although there is evidence from earlier European literature that clinical descriptions matching this disorder were available in the 1920s. Asperger's work was largely ignored until the seminal article by Wing, however, which led to a resurgence of interest in this diagnostic concept. Asperger disorder (AD) was only introduced as a separate diagnostic category in the latest revisions of ICD-10 and DSM-IV. Epidemiologic research on this disorder has only started in recent years and therefore data are still scarce on the prevalence of this syndrome. This article reviews available epidemiologic surveys that have shed light on the prevalence of AD.