OBJECTIVE： To systematically evaluate the effects of MTHFR， RFC1 and MDR1 gene polymorphisms on high- dose methotrexate-induced ADR in osteosarcoma patients， and to provide evidence-based reference for individual medication of high-dose of methotrexate. METHODS： Retrieved from Medline， Embase， clinical trials.gov， CNKI， Wanfang database and CBM， cohort studies about the association of MTHFR C677T/A1298C， RFC1 G80A， MDR1 C3435T gene polymorphisms with high-dose methotrexate-induced ADR were collected. After data extraction of clinical studies met inclusion criteria， and quality evaluation with the Newcastle-Ottawa Scale， Meta-analysis and descriptive analysis were performed for outcome indexes as the incidence of high-dose methotrexate-induced ADR （hematotoxicity and myelosuppression， hepatotoxicity， nephrotoxicity， oral mucositis， digestive tract toxicity and overall adverse events） with Rev Man 5.3 and Microsoft Excel 2016 software. RESULTS： Totally 8 cohort studies involving 608 patients were included； 6， 5， 4 and 2 studies reported outcome indexes related to MTHFR C677T/A1298C， RFC1 G80A and MDR1 C3435T gene polymorphisms respectively. Meta-analysis and descriptive analysis showed that MTHFR C677T gene polymorphism was significantly associated with the risk of G3-4 renal toxicity [TT/CT vs. CC： OR＝12.35， 95％CI＝（3.28，46.42）， P＜0.001]， G3-4 oral mucositis [T vs. C： OR＝2.04， 95％CI＝（1.06，3.93）， P＝0.03]， oral mucositis [（TT vs. CT/CC： OR＝2.27， 95％CI＝（1.20，4.27）， P＝0.01] and renal toxicity （P＜0.05）； MTHFR A1298C gene polymorphism was associated with G3-4 hepatotoxicity， G3-4 nephrotoxicity and G3-4 oral mucositis， without statistical significance （P＞0.05）. There was no significant correlation between RFC1 G80A polymorphism and hemotoxicity， hepatotoxicity， nephrotoxicity and digestive tract toxicity （P＞0.05）. MDR1 C3435T polymorphism was significantly correlated with oral mucositis （P＜0.05）， but not with hematotoxicity and hepatotoxicity （P＞0.05）. CONCLUSIONS： MTHFR C677T mutation can increase the risk of high-dose methotrexate-induced ADR. There is no significant association between MTHFR A1298C polymorphism and high-dose methotrexate-induced ADR. There are few studies on RFC1 G80A or MDR1 C3435T polymorphism and high-dose methotrexate-induced ADR， and their association is unclear.