Background. Hashimoto's encephalopathy (HE) is a rare autoimmune syndrome characterized by various neuropsychiatric manifestations, responsive to steroid treatment and associated with Hashimoto's thyroiditis. There are only a few reports suggesting that intravenous immunoglobulins (IVIG) might represent an efficacious treatment modality for the severe steroid-resistant HE cases. We presented a patient with HE who developed a complete recovery after the IVIG therapy followed by a long-lasting remission. Case report. We described herien a female patient with the one-year history of autoimmune thyroiditis before the development of neuropsychiatric manifestations. In May 1999, a 38-year-old woman presented at the Institute of Neurology, Clinical Center of Serbia, Belgrade, with the brain-stem syndrome which responded well to steroid treatment. After detailed examinations, the diagnosis of Hashimoto's encephalopathy was established. Two years later, in June 2001, new manifestations (unsteadiness in gait, personality changes, seizures, and persistent headache) gradually developed during a 6-month period. Response to steroids was unsatisfactory and partial, since headaches and personality changes had continuously worsened. In January 2002, the patient received IVIG (0.4 g/kg body weight daily for 5 days). Gradual improvement was noticed and a complete recovery developed over the following weeks. Up to March 2009, during a 7-year follow-up period, remission persisted. Conclusion. To our best knowledge, this is the first report of a long-lasting remission of Hashimoto’s encephalopathy after IVIG therapy. Therefore, this case further supports administration of IVIG, as a potentially beneficial treatment modality, in severe cases of Hashimoto's encephalopathy which are completely or partially resistant to steroids.