This experiment was carried out to evaluate the effect of early mouse embryonic development in vitro by co-culture with bovine and porcine oviductal epithelial cells (BOEC and POEC). The 2-cell embryos were collected from the oviducts of the superovulated and mated cultured in D-PBS /15% FCS at 48 hours after hCG injection. The in vitro developmental rate of blastocyst formation in the embryos were examined under the fllowing treatments; 1) TCM 199 added 15% HCS, 2) Ham's F-10 added 15% HCS, 3) MediCult IVF medium, 4) TCM 199 added 15% HCS + BOEC, 5) TCM 199 added 15% HCS + POEC, 6) Ham's F40 added 15% HCS + BOEC, 7) Ham's F-10 added 15% HCS + POEC,8) MediCult IVF medium + BOEC, 9) MediCult IVF medium + POEC. For a comparative study of in vitro development for 96 hours after hCG injection, were cultured with oviductal epithelial cell and media only. The obtained results were 2-cell embryos developed to the blastocyst stage in TCM 199, Ham's F-10 and MediCult IVF medium at the rates of 84.4,83.2 and 81.6%. respectively. The higher developmental rates(91~97%) of blastocyst formation was appeared when the embryos were co-cultured with a monolayer of bovine or porcine oviductal epithelial cells in TCM 199 or Ham's F-10 and MediCult IVF media. No significant difference in developmental rates was shown between bovine and porcine oviductal epithelial cells but significant difference in co-culture system in comparison between media only system and co-cultures. In conclusions, oviductal epithelial cells, BOEC and POEC, when co-culture with mouse early embryos improved the rates of development, blastocyst and hatching. Therefore, it is suggested that co-culture system using oviductal epithelial cells improve early embryonic developtnent in mouse.