Hashimoto's encephalopathy is a rare autoimmune disease, with symptoms of encephalopathy and high titers of serum anti-thyroid antibodies. Current diagnostic criteria include corticosteroid responsiveness, but in some cases, they are refractory to corticosteroids. In steroid non-responders, other immunomodulatory therapies could be applied. Recently, Rituximab is reported as a safe and effective treatment for Hashimoto's encephalopathy. We report a 50-year-old woman with Hashimoto's encephalopathy presented with confusion and catatonia who was refractory to corticosteroid and immunoglobulin but effectively treated with rituximab.