Two transgenic constructs were co-injected into male pronuclei of CBA/Ca zygotes. The constructs encoded (i) a H-2Kb/HLA-G transgene with the human HLA-G heavy chain (HLA-G; major histocompatibility complex, class I, G) gene inserted between the mouse H-2Kb MHC class I promoter and coding sequence, and (ii) a human B2M transgene (designed with the human beta2-microglobulin gene). (A third transgene was also co-injected as well, but was found not to have integrated into the genome.) The mean copy number of HLA-G genomic DNA per haploid mouse genome was 3 copies. HLA-G expression is observed in pre-implantation embryos and a variety of tissues; expression in the reproductive organs (uterus, ovary, and testes), lung, and liver is much more similar to mouse expression of Qa-2 than to Kb (despite the presence of the H-2Kb promoter and downstream coding sequence), while HLA-G expression in spleen, thymus and kidney correlates better with Kb expression patterns. (J:140011, J:140016)