Heterotopic ossification is the atypical process characterized by de novo bone formation in tissues and can be caused by surgery, trauma and genetic disorders. The most commonly affected sites are the hips, knees, elbows and temporomandibular joints. The aim of the study was to evaluate efficacy of radiotherapy in preventing Heterotopic ossification. Data of 84 eligible patients treated with radiotherapy prophylaxis for Heterotopic ossification between 1997-2017 were retrospectively reviewed. 47 (56%) of the patients were male and 37 (44%) were female. The mean age was 50.4 +/- 14.1 (range: 17-82) years. According to the radiotherapy fields; right hip joint 35 (42%), left hip joint 33 (40%), bilateral hip joint 2 (2%), right elbow 10 (11%) and left elbow 4 (5%). After a median follow up of 104 and 95 months, 1 (7%) patient underwent treatment to the elbow site had evidence of Heterotopic ossification after radiotherapy and 8 (11%) patients underwent treatment to the hip sites had evidence of Heterotopic ossification after radiotherapy respectively. When all patients were examined; gender (p= 0.319), age (p= 0.158), etiology (p= 0.167), treatment area (p= 0.532), radiotherapy technique (p= 0.502) and the time between surgery and radiotherapy (p= 0.469) were not statistically significant according to the risk of Heterotopic ossification formation. Radiotherapy with 800 cGy in single fraction is a safe and effective treatment modality in the prophylaxis of patients at high risk for Heterotopic ossification formation. Fractional treatments can also be used for larger treatment areas, but the experience is limited.