BACKGROUNDThe effect of methotrexate (MTX)-related toxicity on childhood acute lymphoblastic leukemia (ALL) is controversial. Hence, this meta-analysis aimed to investigate the association between ABCB1 C3435 T polymorphism- and methotrexate-related toxicity in pediatric acute lymphoblastic leukemia.METHODSRelevant studies were systematically searched and extracted from multiple databases including PubMed, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang databases up to 1 June, 2024.RESULTSA total of 13 articles met the criteria, including 1506 patients. The results showed that ABCB1 C3435 T polymorphism was significantly associated with MTX-induced hepatotoxicity (CT/TT vs. CC: OR: 2.15, 95% CI: 1.40-3.32). There was no significant difference between ABCB1 C3435 T polymorphism and mucositis, myelosuppression, nephrotoxicity, gastrointestinal toxicity in pediatric ALL treated with MTX.CONCLUSIONSOur meta-analysis suggests that the ABCB1 C3435 T mutation may enhance the MTX-induced hepatotoxicity in childhood acute lymphoblastic leukemia.