The effects of two vitrification protocols on the survival of sheep blastocysts were examined in embryos produced in vitro with sheep oviduct epithelial cells co-culture (CC) or without co-culture (C). Oocytes collected from slaughtered ewes were matured for 24 h, fertilized with fresh ram semen for 20 h and cultured in SOF medium for up to 9 days in vitro. For vitrification, blastocyst stage embryos were assigned to two equilibration groups (20% ethylen glycol (EG) or 10% glycerol (G) for the first equilibration), and as the second equilibration they were kept in 20% ethylen glycol plus 10% glycerol for 5 minutes. After 30 sec in vitrification solution (25% ethylen glycol + 25% glycerol), they were immediately immersed into liquid nitrogen. After thawing procedure, embryos were transferred into 0.25 M sucrose for 5 min, washed in Hepes buffered synthetic oviduct fluid (HSOF) and cultured in SOF medium for 24 h. Cleavage rates were 75.2% in C and 74.2% in CC groups, and blastocyst rates were 14.4% in C and 17.1% in CC groups. After in vitro culture of vitrified-thawed blastocysts, survival rates were 62.1, 38.4, 30.2, and 39.3% in C-EG, CC-EG, C-G and CC-G groups, respectively. This study shows that vitrification of sheep embryos using ethylene glycol instead of glycerol as a first equilibration cryoprotectant could give reasonable survival rates and that co-culture of embryos with sheep oviduct epithelial cell has no beneficial effect on vitrification of embryos. Keywords: Co-culture, equilibration medium, in vitro fertilization, sheep vitrification.