Embryonic development requires close apposition of the blastocyst to the luminal surface of the uterine epithelium. As the first site of contact between fetal and maternal tissue, the uterine epithelium undergoes specialised changes allowing it to become receptive to attachment. These changes can vary across mammalian species. However, there are general similarities across all live-bearing taxa. In macropodid marsupial pregnancy, this attachment occurs in the last third of pregnancy after the loss of the shell coat which surrounds the developing embryo. This interaction potentially causes a maternal response to the embryo as a foreign body. In this study we have used gene expression data and IHC techniques to characterise the gene expression and localisation of MUC1 in the uterus during pregnancy in the tammar wallaby (Macropus eugenii). We show that, like in human pregnancy, there is an upregulation of MUC1 gene expression at receptivity and attachment which corresponds with localised staining of MUC1 to the uterine epithelium of gravid uteri. The presence of this mucin provides evidence for a maternal inflammatory response in macropodids, like the inflammatory attachment reaction described in the opossum during this crucial stage of pregnancy.