Although the pathogenesis of Behcets disease (BD) is not fully elucidated, a genetic susceptibility to the disease appears to be affected by a polygenic inheritance, including the major histocompatibility complex (MHC) and non-MHC genes. As is true for the well-known regional differences in the disease expression of BD, a genetic susceptibility to BD appears to be different in various ethnic groups. Although HLA-B51 is a genetic factor with the strongest association in most ethnic populations who reside in countries adjacent to the ancient Silk Road, it is still uncertain whether this HLA molecule is directly involved in the pathogenesis of BD. In addition to HLA-B51, the association of BD with the MICA gene has been reported to be the consequence of linkage disequilibrium with HLA-B51, whereas the TNF-1031C allele among TNF gene polymorphisms has been observed to be another risk factor independent of the presence of HLA-B51 in UK Caucasoid patients with BD. Recently, intensive investigations on non-MHC genes, some of which are noted to be associated with a susceptibility to BD in several ethnic groups, are under way.