After reading this chapter the readers will be familiarize with the oocyte vitrification and embryo vitrification. Vitrification is a cryopreservation procedure by which an aqueous solution is solidified into a glassy phase at low temperatures. The methodology used for oocyte and embryo vitrification may differ significantly between laboratories especially when different devices and solutions are used. The basic procedure is simple and quick. Oocytes or embryos are exposed to a hypertonic solution composed of penetrating concentration of cryoprotectants (CPAs). At this point, water is removed from the cells to adjust osmolarity while CPAs begin to flow into them. The degree of permeability depends on the stage of embryo development and the type of CPA. The premise in the vitrification approach has been that the higher the cooling rate, the greater the likelihood that true vitrification can be achieved. The cooling rate achieved will depend on the device and the volume of solution.