Patients with primary bone malignancies must be treated by specialized multidisciplinary teams composed of pathologists, surgeons, orthopedists, oncologists, radiologists and radiotherapists, all with experience in the diagnosis and treatment of these tumors. If a malignancy is suspected, the biopsy must also be performed in such a center. Biopsy is part of the treatment and must be done by a senior surgeon, before starting specific treatment. Indeed, inappropriate biopsy can compromise the patient's functional prognosis and sometimes the vital outcome. The biopsy can be done percutaneously under radiological control with a True-cut needle or a trocart to obtain cores of pathological tissue. The pathologist must be well-versed in bone disorders. Open surgical biopsy is preferable for primary bone tumors, especially when a cartilaginous tumor is suspected. A short incision is used, situated on the same approach as that which will be used for surgical resection of the tumor, so that the biopsy scar is excised along with the tumor, in a single block. Surgical treatment of primary bone malignancies requires extensive resection, i.e. excision of the affected bone segment and any invaded soft tissues, as a single block, without breaching the tumor, and preserving a peripheral margin of healthy tissue. In most cases, reconstruction is necessary to preserve the function of the resected region. It is based on standard orthopedic techniques, namely osteosynthesis, bone grafts (autografts and allografts), prostheses of variable size, or a combination of prostheses and allografts (composite reconstruction). Amputation is only indicated if conservative resection is impossible. It has been shown that conservative resection, now possible in about 80% of cases, does not reduce the survival chances of patients with osteosarcoma. The indications for amputation include massive tumors invading vessels and nerves, resection of which would leave the limb non functional, as sell as tumor infection (often secondary to biopsy), inappropriate biopsy (infection of vessels or periarticular muscles, etc.), and local relapse. Amputation must respect the same oncologic principles as conservative resection.