The distribution of HSP70-1 promoter alleles was studied in 90 adult Caucasian RA patients (65 European and 25 Asian Indian) and 113 normal control (60 European and 53 Asian Indian). The HSP70-1 promoter alleles were defined by oligonucleotide typing of polymerase chain (PCR)-amplified genomic DNA. The prevalence of HSP70-1 promoter allele "B" was significantly (p < 0.0004, pc < 0.0012; RR = 5.1) higher in RA patients (22.2%) compared to normal controls (5.3%). It is likely therefore that HSP70-1 promoter allele B is associated with susceptibility to RA.