It is known that HLA-B60/B61 heterozygotes often cannot be distinguished from HLA-B60/B60 homozygotes by serological analysis, because monospecific anti-HLA-B61 serum is seldom availahie. Moreover, it is sometimes difficult to discriminate B60/B48 or B61/B48 heterozygotes from B60 or B61 homozygotes by serology. In order to overcome these difficulties, we established a system for discriminating HLA-B60, B61, and B48 groups by means of polymerase chain reaction with sequence specific primers(PCR-SSP) using genomic DNA. By using this system, all the examined samples were easily judged for positivity of B60, B61 or B48 group.