Heterotopic Ossification (HO) is a distinct clinico-radiological entity acccounting for post treatment morbidity in post arthroplasty and trauma patients. Radiotherapy is an effective modality for prophylactic treatment in this condition. The correct timing of delivery of radiotherapy can mitigate HO in a vast majority of patients. The pathophysiology along with current concepts of management of disease are outlined in this article with emphasis on the use of radiation for prophylaxis of HO.