According to the DSM-IV, the autism diagnosis always has priority over the Asperger syndrome (AS). If a patient meets the criteria for autism, the diagnosis of AS is ruled out. However, since Lona Wing reexamined Asperger's original description and noted the similarities between autism and AS, whether autism, especially high-functioning autism (HFA), and AS were the same disorder or not has been controversial. There is no reason why we distinguish HFA from AS with regard to general intervention and social and communication skill training. From a view point of clinical features, cognitive neurophychology and neurobiology, the differentiation between HFA and AS is not clear. There are few reports on outcome in HFA and AS. Whereas, it is suggested that HFA and AS may be different in social problems such as suicide attempt. Researches on the differentiation between HFA and AS are to be needed in future.