Abstract: Objective: To investigate HLA-DM(DMA and DMB) gene polymorphisms and its clinical significance in patients with rheumatoid arthritis in Chinese population. Methods: Ninety-six RA patients and 100matched control subjects were genotyped in the third exon of HLA-DM gene by polymerase chain reaction/sequence specific oligonucleotide probe(PCR/SSOP). Meanwhile,the HLA-DRB1*0405positive individuals were screened by PCR/restriction fragment length polymorphism(PCR/RFLP). Results: No significant difference in the distribution of the DMA and DMB alleles was observed between RA patients and controls, as well as those between the RA patients with HLA-DRB1*0405and controls. The patients with DMB*0101 gene had a higher frequencies of HLA-DRB1*0405and a higher RF titer than those with DMB*0102allele(P<0. 01or 0. 05). Conclusion: The HLA-DM alleles may not have effect on the susceptibility of RA. However,the DMB*0101allele may play some important roles in the disease severity and activity of RA.