Retinoblastoma is a highly radiosensitive tumor. Numerous techniques have been described to treat primary and recurrent disease with this modality. After enucleation resulted in dramatically improved patient mortality surgeons such as Stallard and Reese developed globe sparing approaches that relied heavily on external beam and brachytherapy techniques. External Beam Radiation Therapy (EBRT) is an effective treatment modality for retinoblastoma that allows for salvage of the eye and the potential for functional vision. Improved delivery techniques and management of complications have led to improved visual outcomes. EBRT has numerous toxicities and adverse effects: including cataract formation, orbital growth retardation and secondary primary malignancies, that limit its role as a primary treatment in most cases. EBRT remains an integral part of retinoblastoma therapy and is particularly effective for unresponsive tumors, those not amenable to focal consolidation and those with extraocular extension.