The cryopreservation becomes a routine practice in IVF laboratories. The improvement of this technique and the research for simple and fast method is essential. Co-culrure system is used to remove the damaging effects caused by freezing. It is now generally accepted that Vero cells provide beneficial effects on improving embryo quality in many anjmal species. The aim of this research was to select a benefitial medium to culture the frozen 8-ceil embryos by vitrifcation. The developmental rate of embryos was used to evaiuate the efficiency of Vero cell for improvernent vitrified embryos. 8-cell embryos were vitried by %40 ethylene glycol and the thawing was done in 0.5M sucrose solurion. The developmental rate of embryos were evaluated in various media during 120 hours. In the, first experiment, the vitrified embryos were cultured in MEMa medium only and resulted in an increase in the percentage of hatching. While culture in R2 sequential medium resulted in low rate of hatching blastocysts, which indicated that R2 medium is not benefit for culture of frozen 8-cell embryos. The results of culture of frozen embryos in MEMa+Vero co-culture medium, had no effect on developmental rate of embryos, while the result of R2+Vero co-culture medium was improved the development rate of embryos. the comparison of MEMa and R2 media done and the reslts demonstrated that MEMa was beuer than R2 by improving development of frozen embryos. A similar comparison for co-culture was done and the results was similar to that culture embryos.