Osteosarcoma,chondrosarcoma and Ewing tumors are the most common primary malignant bone tumors. Due to early hematogenous dissemination, surgery alone is able to cure less than 20% of patients with osteosarcoma. In Ewing-tumors less than 10% of patients will be cured with local treatment alone. By the use of aggressive polychemotherapy, given both pre- and post-surgery, cure rates of more than 50% for Ewing-tumors and about 70% for osteosarcoma could be achieved.Thus,chemotherapy is an indispensable part of the multimodal treatment of these tumor types. Chondrosarcomas are usually more highly differentiated and therefore show a lower rate of metastasis. The use of chemotherapy is not established in these tumors.