Autism, like most psychiatric disorders, covers a spectrum of severity from severely disabling classic autism to milder forms of Asperger’s syndrome which border on normality. The term autism spectrum disorder (ASD) includes autism, atypical autism and Asperger’s syndrome. Some parents consult their GP worried that their child might have autism. Others may attend with a range of concerns that might point to the condition such as problems with hearing, vision, hypersensitivity to sensory stimuli, behaviour management, language impairment or repetitive behaviour. Autism conditions often co-exist with neurological disorders (particularly those including epilepsy), and more than 300 syndromes which include autism have been described.The new NICE guidelines, launched in September 2011, cover children, from birth up to 19 years, on the autism spectrum and build on the guidance published by SIGN in 2007. ASD was once believed to be relatively rare but is now thought to occur in about 1% of children. There is certainly increasing demand for diagnostic services for children and young people. Whether the apparent increasing prevalence signifies an epidemic or an epidemic of discovery is debatable.