Autoimmune encephalitides are being increasingly recognised as important and potentially reversible non-infectious causes of the encephalitic syndrome. Myriad of clinical presentation and lack of symptom specificity leads to a wide differential diagnosis. Failure to diagnose the correct aetiology of an encephalitic syndrome can lead to significant morbidity and mortality. A 57 years old right handed female with no significant medical problems initially presented with left sided limb weakness, difficulty in walking, speech, memory disturbance, ataxia, and headache. She had marked truncal, finger nose and heel/shin ataxias and her symptoms were chronic at the time of presentation. Her left plantar reflex was extensor response. She had bulbar and cerebellar dysarthria. Lumbar puncture showed normal protein (0.53 g/l) and glucose (3.4 mmol/l). The CSF was acellular. Oligoclonal band and CSF serology was negative. Serum copper, ceruloplasmin, AFP, folate, B12, thyroid function, immunoglobulin profile, coeliac screen, paraneoplastic antineuronal and antipurkinje cell antibodies, blood film were all normal. MRI brain and whole spine cord showed white matter T2 hyperintense lesions in the brain and excluded cerebrovascular disease. CT chest/abdomen/pelvis and PET scans were normal. Anti-GAD antibody level in blood was 2 000 000 IU/ml (010), anti-GAD antibody level in the CSF which was 28 000 IU/ml. The ratio between CSF and blood anti-GAD antibody was 0.9. In view of significantly high titre of anti-GAD antibodies, autoimune encephalitis was suspected. She was treated with plasma exchange and intravenous immunoglobulins. Over next 12 weeks her speech, gait, and truncal ataxia improved significantly. Our case highlights the need for aggressive, early and appropriate treatment of patients with autoimmune encephalitis to achieve good outcomes. It is a disease process that if considered early, diagnosed promptly and treated appropriately (including aggressive treatment with therapies such as high-dose steroids, IVIG, plasma exchange, rituximab and cyclophosphamide) can be reversed and the patient restored to their premorbid state.