Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis was first described in young women with ovarian teratoma. Typical presentations include subacute onset of neuropsychiatric symptoms, seizures, altered awareness, movement disorders, and autonomic dysfunction. Growing evidence indicates that anti-NMDAR encephalitis is one of the most common causes of encephalitis in children and young adults. We present a case of a 2 year-old boy with anti-NMDAR encephalitis to illustrate and discuss the differences in neurological presentation, frequency of symptoms, and association with underlying tumor between children and adults.