To review our institutional outcomes of patients treated with radiation therapy (RT) for Graves' orbitopathy (GO), assess the role of orbital reirradiation, and identify prognostic factors of complete response (CR). This is a retrospective review of 211 patients who presented with a diagnosis of GO and received RT between January 2000-2010. RT dose was 20 Gy in 10 fractions. Patient median age was 51 years (range, 15-84 years), median follow-up was 11 months (range, 1-88 months). Patient symptoms included any combination of proptosis (90.9%), extraocular muscle dysfunction (78.9%), soft tissue signs (68.4%), and diplopia (58.4%). Corticosteroids were used as first-line therapy in 20.6% of patients. Among those who achieved either CR or partial response (PR), prognostic factors were evaluated. Stabilization of disease without recurrence was clinically achieved overall in 202 patients (96.7%). At the completion of RT, 176 patients (84.2%) reported a symptomatic improvement of pretreatment symptoms. CR of GO symptoms was achieved using multiple treatment modalities, including RT by 93 patients (44.5%), of which 32 patients received RT only. Corticosteroids were discontinued in 97.8% of patients who received them as initial therapy. Surgical intervention following radiotherapy was required for 144 (68.9%) of all patients. Fourteen patients received orbital reirradiation for persistent or recurrent symptoms. Five of these achieved a CR, and the other nine achieved disease stabilization but retained persistent ocular symptoms. Long-term side effects of RT included dry eyes (12%). Of the prognostic factors we investigated, only gender predicted CR, which was less common in men (33.9%) than in women (49.7%) p = 0.0471. Orbital radiation for GO is an established treatment modality for patients. Orbital reirradiation is beneficial for patients who do not respond to initial RT or experience symptom recurrence without an apparent risk of increased morbidity.