Abstract: Objective Multidrug resistance-associated protein 1 (MRP1) has been reported with a close correlation with tumor multi-drug resistance. Real-time quantitative PCR (QRT-PCR) was performed to detect the MRP1 gene expression in childhood acute lymphoblastic leukemia (ALL) and its clinical significance was analyzed. Methods Sixty-seven denovo ALL patients and 10 healthier children as bone marrow donor were studied. The chemotherapy was given according to CCLG-2008 protocol. SPSS software was employed to analyze the data and p-value below 0.05 was regarded as statistic significance. Results MRP1 expression level showed a close correlation with ALL risk, the median of MRP1 expression was 4.28 (2.75~6.12), 5.62 (4.99~8.60) and 7.56 (3.66~11.13) for standard-risk group (SR), intermediate-risk group (IR) and high-risk group (HR), respectively. MRP1 mRNA expression in T-ALL group was 7.71 (6.49~14.35), which is higher than that of B-ALL (5.18(3.89~8.46)) (P<0.01). The rate of leukemia cells’ sensitivity to prednisone on 7th day was 70.6% in high expression group (n=34), which was significantly lower than that in low expression group (n=33, 90.9%, P=0.035). The complete remission rateon 33th day was 64.7% in high expression group, and 87.9% in low expression group, which showed a significant difference between them (P=0.026). Conclusions In children ALL, the expression of MRP1 is closely related with immunophenotyping, treatment response, hazard level and disease relapse.