Schizophrenia shares several genetic features with diseases known to be autoimmune and could therefore be an autoimmune disease itself. Antipsychotic drugs, which are effective in treating the psychotic symptoms of schizophrenia, have one property in common--they block dopamine receptors in the central nervous system. This observation has led to the hypothesis that overactivity of dopaminergic pathways is the cause of the psychotic symptoms, but a seeming anomaly is that the turnover of dopamine is not increased in schizophrenia. Dopamine-receptor-stimulating autoantibodies are postulated to cause the dopaminergic hyperactivity, thereby accounting for the anomaly.