Basigin is a member of the immunoglobulin superfamily and a key molecule related to mouse blastocyst implantation. Whether preimplantation mouse embryos express basigin mRNA is still unknown. The aim of this study was to use a quantitative competitive polymerase chain reaction to assess quantitatively the levels of basigin mRNA in mouse oocyte and preimplantation embryos. Basigin mRNA was detected in the oocyte and all the stages of preimplantation embryos. The levels of basigin mRNA were 0.0606 ± 0.0282 in the oocyte, 0.0102 ± 0.0036 in the zygote, 0.0007 ± 0.0003 in the 2-cell embryo, 0.0031 ± 0.0017 in the 4-cell embryo, 0.0084 ± 0.0024 in the 8-cell embryo, 0.0537 ± 0.0121 in the morula and 0.0392 ± 0.0161 attomoles in the blastocyst, respectively. The levels of basigin mRNA in the oocyte, morula and blastocyst were significantly higher than those in the zygote and embryos at the 2-cell, 4-cell and 8-cell stages. The high level of basigin expression in the blastocyst may play a role during embryo implantation.