In recent years, the frequency of diagnosing autoimmune encephalitis has increased significantly, both in the population of adults and children and adolescents. This fact is undoubtedly related to the dynamic development of new diagnostic methods, as well as the progress of medical knowledge. A particular type of this condition is anti-NMDA receptor encephalitis. Due to the presence of psychiatric symptoms in this disease, psychiatrists are often the first specialists who treat a patient with the above diagnosis. Differential diagnosis is extremely difficult and primarily based on the history and presence of typical clinical symptoms. Therefore, based on a narrative review of the literature on the subject searched by the PubMed, EMBASE, and Cochrane library databases from 2007–2021 with the keywords “anti-NMDAR encephalitis”, “children”, and “adolescents”, the author described the characteristic course of the disease, diagnostic methods used to confirm the diagnosis, and presents current treatment guidelines. Due to high prevalence, anti-NMDA receptor encephalitis is a diagnosis that should be considered in the differential diagnosis in everyday psychiatric practice.