The relationship between the treatment of Graves' hyperthyroidism and the course of ophthalmopathy is rather unclear. Antithyroid drugs may improve eye manifestations, possibly by restoring normal thyroid function and reducing orbit-directed autoimmune reactions, whereas ophthalmopathy may worsen after radioiodine administration or thyroidectomy. This might occur because of a treatment-related release of thyroid antigens and activation of the autoimmune response that might involve the orbit. On the other hand, some authors suggest that complete thyroid ablation, either by radioiodine or surgery, might be beneficial for ophthalmopathy. However, reported effects of radioiodine and thyroidectomy on Graves' ophthalmopathy are conflicting. This may be due, at least in part, to the retrospective feature of most studies and the lack of precise evaluation of ocular involvement. Two prospective studies were performed in which patients with Graves' disease with mild or no ophthalmopathy were randomly assigned to treatment by radioiodine or subtotal thyroidectomy alone or in association with systemic glucocorticoids. Both treatments were followed by a progression of pre-existing mild ophthalmopathy in a substantial proportion of cases: glucocorticoids prevented such an exacerbation. Ophthalmopathy did not develop in patients without clinical evidence of eye disease prior to therapy. Therefore, it is recommended that a course of glucocorticoids be instituted concomitantly with radioiodine therapy or thyroidectomy in Graves' patients with some degree of ocular involvement.