During the past 30 years, the orthopaedic oncology group at the Massachusetts General Hospital has treated 648 patients with osteosarcoma centrally located in the bone. Using records maintained in a specifically designed computer system, a study was done to assess the factors that seemed to influence the survival outcome. The overall survival for the entire series was 68% at an average followup of 6 +/- 4 years. Death occurred at a mean of 3 +/- 3 years. Patient gender had no effect, but age of the patient was correlated with survival data, with the poorest survival for the older patients. Surgical treatment had no effect on outcome, but the Musculoskeletal Tumor Society stage of the lesion, the presence of metastases or local recurrence, and the chemotherapeutic treatment (very dependent on the drugs available and adjuvant versus neoadjuvant administration at various decades) all had a profound effect. In addition, anatomic location, size of the tumor, and percentage of tumor cells killed after neoadjuvant chemotherapy all had an effect on outcome.