Unusual or unexpected effect of treatment Background:Tocilizumab is a therapeutic biologic antagonist of the interleukin-6 (IL-6) receptor that has been approved to treat some autoimmune and chronic inflammatory diseases. This report is of a patient with a history of Graves disease and severe corticosteroid-unresponsive thyroid eye disease that included edema of the optic nerve and choroid, which was successfully treated with tocilizumab. Case Report:A 46-year-old woman with a 4-year history of Graves disease presented with acutely progressive bilateral severe optic nerve compression, severe bilateral optic nerve edema, bilateral restriction of eye movement, and bilateral choroidal folds. The patient was managed with an initial high dose of systemic steroid without any success. She then underwent bilateral orbital wall decompression without any noticeable amelioration. She subsequently received 4 doses of a tocilizumab (8 mg/kg) infusion. This resulted in a considerable decrease in inflammatory signs and improvement in optic nerve function, thereby improving her quality of life. The patient did not have any adverse reactions to the tocilizumab. Conclusions:The findings from this case support recent case reports and clinical trials indicating that tocilizumab may be effective in corticosteroid-resistant thyroid eye disease associated with autoimmune hyperthyroidism.