Background and Clinical Significance: NMDAR autoimmune encephalitis is a rare but potentially life-threatening autoimmune disorder that can be hard to recognize initially because it has nonspecific symptoms. In the early phase of the disease, clinical presentation is often dominated by psychiatric symptoms, which can be misleading. A diagnosis is established by demonstrating specific anti-NMDA receptor antibodies, with cerebrospinal fluid analysis considered the most reliable diagnostic method. Timely initiation of immunomodulatory therapy, including corticosteroids, intravenous immunoglobulins, and therapeutic plasmapheresis, significantly improves disease outcomes, while second-line therapies are used in refractory cases. Case Presentation: A 21-year-old female patient (M.B.) was admitted to the Psychiatry Clinic at the University Clinical Center of Vojvodina due to the sudden onset of behavioral changes, including social withdrawal, absence of verbal communication, and unusual orofacial grimacing. During hospitalization, the patient was intermittently in a state of severe psychomotor agitation and poorly communicative, with pronounced orofacial dyskinesias and involuntary tongue movements. Anti-NMDA receptor autoantibodies were detected in both serum and cerebrospinal fluid, and the patient was subsequently transferred to the Intensive Care Unit of the Neurology Clinic. Due to the lack of an adequate clinical response to pulse corticosteroid therapy, six cycles of therapeutic plasmapheresis were performed. Following this treatment, significant clinical improvement was observed. Conclusions: Timely recognition of this condition and a multidisciplinary approach allow for early initiation of immunomodulatory therapy and significantly improve treatment outcomes.