Schizophrenia usually starts in young adulthood. The cumulative lifetime risk for men and women is similar, although it is higher for men in the age group younger than 40 years. A common categorization of severe mental illness includes the schizophrenic and delusional disorders listed under e.g. categories F20–29 of the WHO International Classification of Diseases (ICD). Characteristic for the schizophrenic disorder is a distortion of thinking and perception and affects that are inappropriate or blunted. Hallucinations, delusional perceptions and delusion of controls are psychopathological phenomena that appear in schizophrenia. Diagnosis and treatment of schizophrenia are often delayed. Schizophrenia is one of the most burdensome and costly illnesses worldwide, because of onset, course and rate of disabilities. Family relationships suffer, if the burden of care is shifted to families. According to the Global Burden of Disease Study, schizophrenia causes a high degree of disability, which accounts for 1.1% of the total DALYs (disability-adjusted life years) and 2.8% of YLDs (years lived with disability). Schizophrenia is listed as the eighth leading cause of DALYs worldwide in the age group 15–44 years, according to the WHO World Health Report: new understanding, new hope, 2001, Geneva. The risk of suicide is very high, 10–13% of people with schizophrenia commit suicide. Comorbid somatic conditions in people with schizophrenia can also lead to premature death. Optimizing the general health needs attention.