The immunology of pregnancy has been mostly investigated in the mouse, although this animal model is clearly inappropriate for several critical aspects of the studies. The contribution of alternative and less known models such as ovine and bovine species should not be neglected. The uterine morphology and the important resistance to invasive surgery, the synepitheliochorial placentation, the long peri-implantation phase associated to a specific signal of maternal recognition - interferon-tau- and the availability of original experimental models including somatic cloning offer unique opportunities of investigation for answering fundamental and applied biological questions. The low and high-throughput analyses of cell and tissue phenotypes have taken advantages from genome annotation and powerful genomic tools including microarrays and functional exploration of a target gene function. Considering present reports and future directions, ruminants can undoubtedly contribute in a relevant way to a better knowledge of the immunological process taking place in a successful, perturbed or failed pregnancy.