Autoimmune encephalitis due to surface antineural antibodies covers a wide spectrum of clinical entities. Encephalitis due to antibodies against the surface antigen of the external portion of the N-methyl-D-aspartate receptor (RNMDA) is the most frequent and best characterized. The case of an adolescent with a clinical picture of neurosychiatric disorder and epileptic seizures of recent onset is presented: he had a positive response for anti-RNMDA antibodies, and a partial response to treatment with corticosteroid therapy and immunoglobulin; therefore, he received additional management with plasma exchange followed by maintenance therapy with immunoglobulin cycles, without the use of immunosuppressants. The results of a long-term follow-up are reported.