Abstract: The purpose of this study was to investigate the developmental potential of the mouse tetraploid embryos by the detection of the cell apoptosis and the expression of Bax and Bcl2 genes in the tetraploid blastocysts.The results indicated that the rate of the blastocyst formation was no significant difference between in the tetraploid embryos and in the diploid embryos in vitro. The result of the differential staining showed that the cell numbers of ICM and TE, the ratio of ICM/Total cells in the tetraploid blastocysts were lower than that in the diploid blastocysts in vitro or in vivo. At the same time,the detection of the cell apoptosis by TUNEL suggested that the index of the cell apoptosis in the tetraploid blastocysts was higher than that in the diploid blastocysts in vitro or in vivo. In addition, the expression of Bax gene in the tetraploid blastocysts was higher than that in the diploid blastocysts in vitro or in vivo, whereas there was no significant different expression of Bcl2 gene among them. The study demonstrated that the quality of the mouse tetraploid blastocysts was much worse than that of the diploid blastocysts in vitro or in vivo, which may cause the abnormal development of the mouse tetraploid embryos.