Autoimmune encephalitis (AE) is a potentially lethal condition that is often misdiagnosed as schizophrenia, due to similarities between the severe mental disorder and autoimmune psychosis (AP). This rapidly evolving topic in both neurology and psychiatry has stimulated much clinical research. There has also been criticism of the validity of the criteria for possible autoimmune psychosis. In clinical practice, it is often difficult to decide how far diagnostic procedures should go in unclear cases. This lecture will aim to summarize the diagnostic findings and present the Neuropsychiatric Checklist for Autoimmune Psychosis as a tool for clinical assessment.