This chapter reviews what limited evidence there is in respect of epidemiology of early onset schizophrenia. Early onset schizophrenia will be subdivided into "very early onset schizophrenia" and "adolescent onset schizophrenia". Rare instances of autism and schizophrenia do occur, and it appears that individuals diagnosed with early onset schizophrenia quite often have some marked autistic symptoms in their premorbid history. Medical syndromes and epilepsy are sometimes associated with Asperger syndrome, but at a considerably lower rate than in classic childhood autism. Disruption of normal language development sometimes co-occurs with the appearance of epileptogenic discharge on the EEG (particularly during sleep). This group of disorders is often referred to as Landau-Kleffner syndrome. There have been few epidemiological studies specifically of adolescent onset schizophrenia. Most of the data on the epidemiology of schizophrenia in the adolescent age group derive from studies that include only a small subgroup of adolescents and young adults.