BACKGROUND : Primary osteosarcoma in elderly patients are rare malignant tumors. Its optimal treatment has not yet been determined. METHODS : This retrospective study included 104 patients aged >50 years with resectable, non-metastatic osteosarcoma treated by the members of the Bone and Soft Tissue Tumor Study Group of the Japan Clinical Oncology Group. The effects of adjuvant chemotherapy were estimated by comparing outcomes in patients who received surgery plus chemotherapy with those who underwent surgery alone. RESULTS : Median age at presentation was 59 years. Neoadjuvant and adjuvant chemotherapy was administered to 83 (79.8%) patients. Patients who underwent surgery plus chemotherapy and those who underwent surgery alone had 5-year overall survival (OS) rates of 68.6% and 71.7%, respectively (p = 0.780), and 5-year relapse free survival (RFS) rates of 48.2% and 43.6%, respectively (p = 0.64). Univariate analysis showed that resection with wide margins was significantly correlated with better prognosis. CONCLUSIONS : The addition of chemotherapy to surgery did not improve OS or RFS in patients aged >50 years with resectable, non-metastatic osteosarcoma. Surgery with wide margins was only significantly prognostic of improved survival. The effect of chemotherapy in elderly osteosarcoma patients was unclear.