Osteosarcoma is a rare malignant tumor of bone that produces osteoid. Most tumors arise in the metaphyses of long bones. At least 80 per cent of patients have subclinical metastases at diagnosis. Successful management of osteosarcoma requires surgical control of the primary tumor and chemotherapeutic control of systemic metastases. Wide resection of primary tumor is often compatible with limb-sparing surgery. Multiagent chemotherapy has significantly enhanced disease-free survival. Osteosarcoma metastasizes to lung and other bones. Aggressive surgical resection can sometimes control pulmonary metastases; bony metastases are almost always followed by death.