Recent studies indicate that certain haplotypes of HLA are frequently associated with Takayasu's disease, and that HLA-A and B loci could determine the predisposition to this disease, especially in women. Ths paper describes two male sibs with Takayasu's disease in whom HLA typing was carried out. In addition, HLA types were determined on A, B, C, and DR loci of all family members. It was found that no haplotypes were shared by the two patients, but that HLA-Bw52, which has been reported to be frequently associated with Takayasu's disease, was found in one of them. The results suggest that the pathogenesis may be multifactorial and not solely linked to HLA.