Osteosarcomas are radioresistant tumors whose first-line treatment is based on chemotherapy and surgery. To better define the role of radiotherapy, we carried out a review of the literature from the 2000s concerning children and adults. Radiotherapy can be offered post-operatively in cases of R1 resection, at a minimum dose of 60Gy. It is also used exclusively for unresectable tumors, with higher doses. The use of hadrons seems promising. Radiotherapy under stereotactic conditions can be considered for lung and bone metastases. Finally, adaptation of systemic treatments is necessary during irradiation.