The distribution of HLA-DPB1 alleles was studied in 94 adult Caucasian RA patients (65 = seropositive, 29 = seronegative) and 40 normal controls. The DPB1 alleles were defined by oligonucleotide typing of polymerase chain (PCR)-amplified genomic DNA. The prevalence of the DPB1*0402 allele was higher in seropositive RA patients and DPB1*0201 was higher in seronegative RA patients. These differences were not significant, however. It is likely that DPB1 alleles do not play an important role in susceptibility to RA.