ObjectiveTo analyze the diagnosis status and epidemiological characteristics of anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDAR encephalitis) in the Sichuan province of China. MethodsIn the retrospective survey study, data of cases suspected as autoimmune encephalitis in Sichuan province from January 2012 to February 2017 were collected from the third-party test center.The diagnosis status and epidemiological characteristics of anti-NMDAR encephalitis were analyzed. Results① A total of 1 714 cases had been suspected as autoimmune encephalitis with anti NMDA receptor antibodies tested.In hospitals of capital city, cerebrospinal fluid or serum of 1 511 cases were tested since 2012.In other cities, 203 cases were tested since 2014.Hospitals with anti NMDA receptor antibodies tested increased by year.The cases distributed in the department of neurology, psychology, pychiatric, ICU, pediatrics, geriatrics, otolaryngology, infection, the mergency department and pneumology.② Cases with anti NMDA receptor antibodies tested increased by year.A total of 155 cases were confirmed as anti-NMDAR encephalitis, with the average onset age of (27.9±12.0) years ranged from 9 years to 77 years, including 89 women and 66 male.The female average age were (26.5±11.31) years, while the male were(29.0±13.0) years.③ Among the 155 confirmed cases, 127 cases with detailed clinical data were analyzed further.Seizure and behavior disorder were the main symptoms at onset.Among the 127 cases, 107 cases were misdiagnosed at their first hospital visit, with the misdiagnose rate of 84.3%.18 cases were reported with tumors (17 female), mainly with teratoma(11/17). ConclusionIn Sichuan province, the doctors of hospitals in non-capital city should strengthen the identification of autoimmune encephalitis.Anti-NMDAR encephalitis could be misdiagnosed easily and non-neurological physicians should also take attention;