We previously reported that BCG-induced anergy in mice (evaluated by delayed hypersensitivity to sheep erythrocytes) is unigenic and influenced by genes linked to the immunoglobulin heavy chain allotype (Igh). Using congenic mice (either H-2k or H-2b), we could not detect H-2-linked control of anergy. The current study re-examines this issue by using both BXD (H-2b or H-2d) and BXH (H-2b or H-2k) recombinant inbred (RI) mice as well as H-2 recombinant mice of different haplotypes. BXD RI (H-2b) mice were more anergic than BXD RI (H-2d) animals. Also, BXD RI (Ighb animals were more anergic than BXD RI (Ighc) mice. By evaluating combinations of H-2 haplotypes and Igh allotypes, we found the most anergic animals to be H-2b, Ighb. BCG-induced anergy then appears to be influenced by genes linked to both the H-2 and Igh complexes. BCG-induced anergy developed in H-2 recombinant mice (C57BL/10 background) that were either H-2b or H-2k, but not in H-2d animals. Experiments in the B10.A mouse suggested that genes within the H-2K through H-2I were influential. A more definitive map is presented of Igh-linked genes influencing anergy, suggesting that these genes are approximately 23 recombination units on the centromeric side of Igh-1 between Igh-Src and Lyb-7.