The study was aimed to explore the possible association between HLA-DRB1 allele polymorphism and the susceptibility to leukemia in Gansu Chinese Han nationality and to find the genes susceptible to leukemia. HLA-DRB1 genes in 74 patients with leukemia from northwestern China and 82 healthy Chinese controls were determined by polymerase chain reaction and sequence-specific oligonucleotide probe hybridizations (PCR/SSO) DNA analysis. The results showed that as compared with control, the allele frequencies of HLA-DRB1*03 (chi(2) = 8.125, P = 0.004), HLA-DRB1*07 (chi(2) = 13.526, P = 0.000), HLA-DRB1*08 (chi(2) = 18.855, P = 0.000), HLA-DRB1*13 (chi(2) = 7.039, P = 0.008) significantly increased in AML group. The allele frequencies of HLA-DRB1*07 (chi(2) = 5.689, P = 0.017), HLA-DRB1*11 (chi(2) = 7.73, P = 0.005), HLA-DRB1*12 (chi(2) = 4.234, P = 0.040), HLA-DRB1*13 (chi(2) = 38.333, P = 0.000) significantly increased in CML group. The allele frequency of HLA-DRB1*01 (chi(2) = 5.294, P = 0.021) significantly increased in ALL group. It is concluded that the susceptibility to AML in Gansu Han nationality is positively related to HLA-DRB1*03. 1*07.1*08.1*13. CML positively correlates with HLA-DRB1*07. 1*11.1*12.1*13, and ALL may be positively in relation with HLA-DRB1*01. Allele polymorphism is associated with the leukemia occurrence.