Background: Prognosis for patients with relapsed/metastatic osteosarcoma is dismal and the optimal treatment strategy remains to be refined. Sorafenib and sorafenib plus everolimus are the only two second-line targeted therapies recommend by FDA. The median progression-free survival (PFS) was 4–5 months. In this study, the efficacy and safety of apatinib, another oral tyrosine kinase inhibitor targeting VEGFR-2, were evaluated in patients (pts) with inoperable high-grade osteosarcoma progressing after standard multidisciplinary treatment. Methods: This retrospective study reviewed the medical records of 26 pts with metastatic osteosarcoma who received apatinib at a dose of 500 mg qd or 250 mg bid after failure of standard treatment including doxorubicin, cisplatin, ifosfamide and high-dose methotrexate from Jul 2015 to Nov 2016. Results: Among all pts, 25 (96.2%) had pulmonary metastases and 4 (15.4%) had metastases in the bone (Table). Eleven pts achieved partial response, 10 stable disease and 5 progressive disease, yielding an objective response rate of 42.3% and a clinical benefit rate of 80.8%. Followed up to Dec 31 2016, the median PFS was 8 months (95%CI, 3.2–12.8 months), and the median overall survival (OS) was not reached. The 12-month PFS and OS rates were 22.5% (95%CI, 1.6%–58.1%) and 68.7% (95%CI, 37.5%–86.5%), respectively. Noteworthy, the 12-month PFS rate for patients treated with apatinib in the second-line setting was 51.3% (95%CI, 9.1%–83.1%). The most frequent treatment-related adverse events (AEs) were hand-foot skin reaction (HFSR) (84.6%), hypertension (46.2%), and diarrhea (23.1%). Severe AEs included grade 3 HFSR (7.7%) and hypertension (3.8%). No unexpected AE was found. Conclusions: Apatinib was well tolerated and demonstrated activity as a second- or later-line treatment in patients with metastatic osteosarcoma, which deserves further investigations.