The cryopreservation of mammalian embryos has become a well-established procedure. However, unfertilized oocytes are only rarely cryopreserved due to their sensitivity to environmental factors. In this study, CB6, F1 mouse oocytes (n=1321 unfertilized) were vitrified after exposure to VS1 medium. After thawing at 37°C for 20 second, oocytes were fertilized in vitro. The proportion of blastocyst rates at 96 h post insemination were untreated (group A), VS1 exposed (group B) and vitrification (group C) groups were ; 77.08%, 62.74% and 31.42% respectively. These results show that mouse oocytes can be frozen successfully in VS1 medium by vitrification technique.