To investigate whether Ghrelin plays a role in mouse preimplantation(Mus musculus)development, in vivo embryos at different stages were obtained, and the relative expression level of Ghrelin mRNA was detected with real-time quantitative PCR. The results indicated that Ghrelin mRNA was expressed in early embryos in various developmental stages. The expression was the lowest at 2-cell stage, while reached the highest in 8-cell embryos, and thereafter decreased again. These results suggest that Ghrelin may play essential roles in mouse preimplantation embryo development.