AbstractAutistic spectrum disorders (ASD), are a group of disorders characterised by qualitative abnormalities in social and emotional behaviour and are associated with restricted, stereotyped and repetitive interests and activities. There has been considerable understanding of ASD in recent years. This educational review paper focuses on four areas of interest and relevance to trainees preparing for the membership examination of the Royal College of Psychiatrists (MRCPsych): (a) diagnosing ASD; (b) epidemiology of ASD; (c) aetiology, including genetic, cognitive and neurochemical/neuropathological theories in ASD; and (d) treatment of ASD. Relevant papers are discussed and recommendations for further reading are provided.