Background: The application of cryopreservation in human and animal reproductive medicine has stimulated several studies about the effects of low temperatures and freezing processes on cells and tissues, in order to develop efficient protocols for gamete and embryo preservation. Moreover, cryopreservation is a fundamental tool for the establishment of animal germplasm banks, allowing the preservation of genetic material from several species and breeds or for further study and/or recovery of desirable characteristics. For the success of cryopreservation, the addition of an intracellular cryoprotectant agent in the freezing solution is indispensable. However, issues related to intracellular cryoprotectant agents used, e.g., their metabolism and potential toxicity, must be examined carefully so we can choose the cryoprotectant most suitable for a specific structure. Review: In this regard, this review introduces several aspects of cryopreservation, such as basic principles and methods used (slow freezing and vitrification), describing the fundamental steps of cryoprotectant agent's exposure, cooling, storage, thawing or warming and removal of the cryoprotectant agent. The addition of an intracellular cryoprotectant to the freezing solution is essential, but does not guarantee the success of the cryopreservation protocol, due to its toxic effect, which requires a perfect balance between cryoprotectant concentration, temperature and exposure time to the structure which will be cryopreserved. Some studies attribute the toxicity of these agents mainly to the secondary metabolites formed when the cell resumes its activity and gradually begins to metabolize the cryoprotectant agent. These secondary metabolites, such as lactate resulting from the degradation of propanediol and the production of oxalic acid after the catalysis of ethylene glycol, can interfere in a number ways on cellular homeostasis, resulting from an acid-base imbalance with cellular acidosis until the uncoupling of oxidative phosphorylation in the mitochondrial membrane, preventing the production of adenosine triphosphate. In addition, there are characteristics of tissue's formation and metabolic peculiarities inherent to each species, resulting in differences in optimal conditions required to maintain the biological properties of cells after thawing. Therefore, in addition to the knowledge about the chemical and biological characteristics of the most suitable cryoprotectant agent for a given species, it is also necessary to adjust the concentration and exposure time to it, allowing a more efficient preservation of various cell types. Conclusion: Cryopreservation is a valuable tool for female gametes preservation, providing support for several reproductive biotechnologies allowing safeguard the genetic material and facilitating its propagation. However, the success of this procedure depends on the proper use of a cryoprotectant agent, which application, although essential, can cause irreversible cell damage that can result in cellular death. Although there is no ideal cryoprotectant agent, able to protect completely the cell at low temperatures and also to be free of toxicity, it has been demonstrated that the cryoprotectants currently employed enabled the preservation of oocytes and ovarian tissue allowing the in vitro production of embryos and the restoration of fertility after transplantation.