The relative immunogenicity of the H-7.1 alloantigen has been shown in a previous communication to be regulated by a gene in the D region of the mouse major histocompatibility (H-2) complex. The level of relative immunogenicity was inferred from survival times of H-7.1-incompatible skin grafts donated by donors with different H-2 haplotype origins of H-2D region genes. In this communication we ...