In the context of discovery of synaptic autoantibodies in patients with encephalitis, autoimmune psychosis with acute encephalopathy and psychosis as the main symptom has been proposed on the basis of those autoantibodies. Correspondingly, autoantibody-related mechanisms have also been proposed in schizophrenia. This paper outlines the relationship between schizophrenia and autoimmune psychosis by describing the relationship between synaptic autoantibodies and schizophrenia and our findings regarding anti-NCAM1 autoantibodies in schizophrenia.