Encephalitis caused by N-methyl-D-aspartate receptor antibodies is associated with auto antibodies against the heteromeric NR1/NR2 units of NMDA receptors. This type of encephalitis occurs more commonly in young adults, most of them women, and shows a good response to known treatments. Clinical features include neuropsychiatric manifestations, advancing through a series of stages up to a gradual recovery. This type of encephalitis can be associated with the presence, or lack thereof, lesions caused by tumors. It can easily be mistaken with infectious encephalitis, therefore is important to recognize its clinical features for an appropriate diagnosis and treatment in order to prevent higher morbidity and mortality. In this article, I describe a case study of autoimmune encephalitis caused by NMDA receptor antibodies in a twenty-two year old man, admitted to the Enrique Garcés Hospital in Quito-Ecuador, and I make a literature review on this pathology.