Received November 05, 2008
Accepted February 16, 2009

Objective: compare the results of a new blastocysts vitrification technique using conventional straws with the results of day 2 and day 3 embryos slow freezing. Methods: fifty-two cycles of blastocysts vitrification and warming, which resulted in 43 transfers (group 1), and 60 cycles of day 2 and day 3 embryos slow freezing and thawing, which resulted in 51 transfers (group 2), were done at Pró-Criar / Mater Dei Clinic in the period of January 2005 to December 2007. These 94 transfers of vitrified blastocysts or frozen embryos had been analyzed retrospectively. Results: the implantation and pregnancy rates were significantly higher in group 1 (34.7% and 48.8%) compared to group 2 (10.7% and 17.6%). There was no statistically significant difference of pregnancy and implantation rates between blastocysts vitrified in the fifth or sixth day. Also there was no difference of pregnancy and implantation rates between frozen embryos in the second or third day of development. Conclusion: this new blastocysts vitrification technique decribed in this study showed good results of survive, implantation and pregnancy compared to the technique of slow freezing of embryos in the second and third days of culture. Prospective studies are needed to confirm the superiority of this new technique.