The aim of this chapter is to evaluate the current situation concerning oocyte freezing. Clinical outcome using slow cooling and vitrification was assessed in the literature and in our clinic to evaluate possible differences using either of the protocols. Both techniques were successfully applied with a comparable number of healthy babies being born using either of the protocols. Nevertheless, slow cooling has been widely applied whereas vitrification has been primarily used in egg donor programs thereby influencing the outcome rates. A randomized study in a comparable group of patients would be appropriate to define the best protocol to apply.