Abstract: Objective: To investigate the association between the genes of human leukocyte antigens(HLA)-DR1-DR10 and the clinical features,stages by X-ray image as well as the laboratory test results of rheumatoid arthritis(RA) in the population of Han nationality in northern Anhui province.Methods: The method of amplification with polymerase chain reaction-sequence specific primer(PCR-SSP) was used to determine the HLA-DR1-DR10 gene types in 80 patients with RA and 40 healthy controls from Han nationality in northern Anhui.The association between the gene types of HLA-DR and the clinical features,X-ray stages of articulations and the laboratory test results were analyzed.Results: The frequency of HLA-DR4 alleles was 35% in the RA patients and 15% in the healthy controls.The frequency of HLA-DR4 alleles was significantly higher in RA patients than that in normal subjects(P<0.05).The frequency of HLA-DR4 alleles was higher in the group with positive sera of the rheumatoid factor(RF) and subsequent lung diseases(P<0.05 and P<0.005).The level of RF,anti-CCP antibody and erythrocyte sedimentation rate(ESR)in patients carrying HLA-DR4 gene was significantly higher than that of other patients(P<0.05-P<0.01).The time of morning stiffness was longer in the patients with HLA-DR4 allele positive(P<0.001).The function and X-ray staging of articulations of class Ⅲ or Ⅳ were more frequently seen in patients with HLA-DR4 positive than in others(P<0.01).Conclusions: The susceptibility of RA is related to HLA-DR4 allele in the population of Han nationality in northern Anhui.HLA-DR4 allele may be related with the time of morning stiffness,level of RF and anti-CCP antibody,ESR and the degree of sclerotic erosion.Patients with HLA-DR4 positive are more liable to acquire subsequent lung injury.