High expression of cellular asparagine synthetase (AS) is a causative factor for the resistance of leukemic cell to L-asparaginase therapy. This study was aimed to find single nucleotide polymorphism (SNPs) in the promotor region of asparagine synthetase (AS) gene and to determine if these SNPs have influence on the transcriptional activity of AS promotor. The DNA sequences of AS promoter (pAS) from 82 leukemic children and 45 controls were determined to screen for SNPs in this region and the AS mRNA level in these samples was quantified using real-time PCR assay. The results indicated that three SNPs were found in the sequenced pAS fragment. They were -239C/T, -92G/A and -62A/T respectively. The frequency of -92A allele was higher in leukemic samples than that in nonleukemic control (P<0.05). The gene expression level differed among the individuals with genotype of the -92G/A SNP, and the descending order was as follows: GA heterozygote > AA homozygote > GG homozygote. It is concluded that some features in leukemia might associate with SNP on -92A locus, and this SNP in pAS can be one of the factors influencing transcriptional activity of AS gene. The existence of the -92A allele variant contributes to a high expression of AS gene.