In 19 families with 97 children the segregation of Rga (Rodgers) was found to be compatible with Mendelian inheritance and five backcross and 14 intercross families were found among HLA and Bf typed families. Close linkage (lods + 17.82) without recombination was found between Rg and the HLA region, with a direct count of 96 nonrecombinant meioses for Rg-HLA-B. Rg- was strongly associated with HLA-B8 (29 of 30 haplotypes) and probably associated with Bw40, but did occur on other HLA-B haplotypes. By inference Rg- is negatively associated with Ch- (Chido). The Rg-Ch- haplotype has not been observed. Rga and Cha may or may not be coded for by different sites of the same cistron closely linked to HLA-B:C and cannot as yet be excluded from being parts of B or C.