Backgroud Few studies have described the characteristics and prognostic factors of elderly patients with osteosarcoma. We ret?rospectively investigated clinico?pathological features and prognostic factors in osteosarcoma patients>40 years old. Methods Patients with high?grade osteosarcoma>40 years old who were treated at our institutions from 2000 to 2016 were re? cruited for this study. Information on patient, tumour, and treatment?related factors was collected and statistically analyzed. The median follow?up was 26.5 months (range, 5-139 months) for all patients. Results Fifty patients (30 males and 20 females) were included. The median age at diagnosis was 59.5 years (range, 41-81 years). The primary lesions were found in the limbs in 32 patients, trunk in 12, and craniofacial bones in six. Primary and sec?ondary osteosarcoma occurred in 41 and 9 patients, respectively. Eight patients exhibited initial distant metastasis. Definitive sur?gery and chemotherapy were performed in 39 patients each. The rate of good responders after neoadjuvant chemotherapy was 38%. The five year overall survival (OS) rates for all patients and those without distant metastasis at diagnosis were 44.5% and 51.1%, respectively. Multivariate analysis showed that definitive surgery was the only significant prognostic factor in non?metastatic pa?tients. The five year OS and disease?free survival (DFS) rates for non?metastatic patients who received definitive surgery were 64.3% and 60%, respectively. Among these patients, neoadjuvant and/or adjuvant chemotherapy significantly improved both OS and DFS. Conclusions Complete surgical resection and intensive chemotherapy should be performed for osteosarcoma patients>40 years old despite distinct clinicopathological characteristics from those of younger patients.