Objective To explore the expression of PD-1 and CTLA-4 in osteosarcoma and their clinical significance. Methods Fifty-eight cases of osteosarcoma encountered from 2007 to 2016 were enrolled. The expression levels of PD-1 and CTLA-4 were detected through immunohistochemistry (EnVision method). Results PD-1 was positively expressed in 31 (53.4%) cases and negatively expressed in 27 (46.6%) cases. CTLA-4 was positively expressed in 19 (32.8%) cases and negatively expressed in 39 (67.2%) cases. A total of 12 (20.7%) cases were PD-1 and CTLA-4 double positive, whereas 20 (34.5%) cases were double negative, and 26 (44.8%) cases were single positive. The positive expression of PD-1 was correlated with neoadjuvant chemotherapy, tumor metastasis and relapse, and shortened survival time (P < 0.05). The positive expression of CTLA-4 was partly related with late Ennecking stage (P=0.051). Double positive expression was related to the highest tumor metastasis and relapse rates and the worst prognosis (P < 0.05), compared with double negative and single positive expression. Conclusion Positive expression of PD-1 and CTLA-4 in osteosarcoma is associated with worse prognosis, whereas double positive expression is associated with the highest tumor relapse and metastasis rates and shortest survival time. These results are potential valuable references for osteosarcoma immunotherapy.