fa پژوهشي اصیل Original Research <div style="text-align: justify;"><strong>Background:</strong> Autoimmune encephalitis is being diagnosed more and more often in the pediatric age group.&nbsp;It should be suspected in children with psychiatric symptoms, encephalopathy, abnormal movements or epileptic&nbsp;seizures. The most frequent autoimmune encephalitis in the pediatric is anti-N-methyl-D-aspartate (anti-&nbsp;NMDA) receptor encephalitis.&nbsp;<br> <strong>Case report:</strong> We report a four-year-old boy with encephalitis signs and symptoms and focal tonic-clonic seizures&nbsp;followed by behavior disorders. CSF and MRI results were normal; but in view of EEG showing delta&nbsp;waves, possibility of autoimmune encephalitis was considered. Then child was treated with plasmapheresis and&nbsp;symptoms were disappeared.<br> <strong>Conclusion:</strong> Autoimmune encephalitis is a treatable disorder and there might be a negative result in patient&rsquo;s&nbsp;CSF antibody&rsquo;s panel of autoimmune encephalitis. Electroencephalogram validated the diagnosis in this case.&nbsp;Considering the fact that autoimmune encephalitis is curable disorder, we recommend that the process of treatment<br> should be started if strong clinical suspicions exists.</div> Anti-NMDAR Encephalitis, Behavior disorders, Plasmapheresis 7 10 http://ijca.iums.ac.ir/browse.php?a_code=A-10-1-66&slc_lang=fa&sid=1 Behzad Haghighi Aski 1003194753284600764 1003194753284600764 No Iran University of Medical Sciences, Tehran, Iran. Fatemeh Parvini 1003194753284600765 1003194753284600765 No Iran University of Medical Sciences, Tehran, Iran. Farhad Abolhassan Choobdar 1003194753284600766 1003194753284600766 No Iran University of Medical Sciences, Tehran, Iran. Ali Manafi Anari 1003194753284600767 1003194753284600767 Yes Iran University of Medical Sciences, Tehran, Iran. Masoumeh Moradkhani-Zadeh 1003194753284600768 1003194753284600768 No Iran University of Medical Sciences, Tehran, Iran.