Several studies have been performed on the association between non-Hodgkin's lymphoma (NHL) and the presence of certain human leukocyte antigens (HLA) class II alleles in Asian countries, and these studies have shown different results, according to the ethnicity, for the frequencies of the HLA class II alleles, and especially for HLA-DRB1. Therefore, the distribution of the HLA-A, B, C, DRB1, and DQB1 alleles in 89 Korean patients with NHL and also in 200 healthy Korean controls was investigated in this study. For the class I alleles, the frequencies of HLA-B51 was increased in patients with NHL and diffuse large B cell (DLBC) lymphoma compared with the normal control. For the class II alleles, the frequencies of the HLA-DRB1*09 and DQB1*03 alleles were increased in patients with NHL and DLBC lymphoma compared with the normal controls. Also, the B51-DRB1*09-DQB1*03 haplotype was significantly increased in the patients with NHL. These results suggest that some genes in HLA-B*51-DRB1*09-DQB1*03 haplotype may contribute to NHL susceptibility in the Korean population.