Orbital radiotherapy (ORT) has a good safety record and has been used to treat moderate to severe thyroid eye disease (TED) for over 111 years. Typically, 20 Gy dose is delivered over ten fractions spread over 2 weeks. Standalone ORT treatment may be considered in a small subset of patients with active moderate to severe TED who are intolerant or unresponsive to the current standard of care, systemic steroids regime with intravenous methylprednisolone (IVMP). Standalone OR may also be considered in long-standing moderate to severe TED to improve diplopia and range of binocular single vision. It is also an option in patients with recurrent disease. The success rate of ORT for TED in published studies is up to 60%. In comparison the response rate is around 51% with oral steroids and 54.3%–77% with intravenous methylprednisolone (IVMP). Combination treatment of ORT with IVMP regime has shown to give excellent outcomes and in others and our experience response rate of around 88%–92%. The case for ORT in active TED is strongest as an adjunctive treatment to systemic steroids predominantly to help with diplopia, range of eye movements and binocular single vision. It also helps reduce the risk of reactivation of thyroid eye disease after stopping systemic steroids. It is also perhaps the treatment option with fewest systemic implications and may be suitable for patients with contraindications to systemic therapies. Long term risks of ORT include cataract (10%), retinopathy in patients with hypertension and diabetes (2%) and an extremely small risk of secondary cancers (0.17%). ORT should be avoided in patients with preexisting diabetic retinopathy and patients less than 35 years of age. Despite the advent of biological therapies as novel treatments, ORT remains an important option in treatment of active thyroid eye disease.