The sequence polymorphism of HLA-DRB1 molecules in 84 rheumatoid arthritis (RA) patients with early RA has been analysed to evaluate whether particular HLA-DR alleles influence disease progression in the early stage of the disease. Clinical data were analysed by grouping the patients according to disease-associated haplotype combinations (DRB1*04,04/DRB1*04,01/DRB1*04,X/DRB1*01,X) in comparison to patients who did not carry these haplotypes (DRB1*X,X). Our results indicate that patients with early RA who are homozygous for DRB1*04 exhibit an elevated inflammatory activity and an increase of joint affections. In addition, the amino acid polymorphism (QR/KRAA) at position 70-74 seems to affect the production of rheumatoid factors. These results support the role of HLA-DRB1 alleles in the pathogenesis of RA and indicate that patients with particular HLA-DRB1*04 haplotype combinations may require intensified therapeutic interventions in the early stage of the disease to prevent disease progression.