Cryopreservation techniques for preserving mammalian oocytes and embryos have advanced in the past two decades, benefiting assisted reproductive technologies. While pregnancies and live births from cryopreserved oocytes and embryos have been successful, there are still challenges to overcome. The success rates of cryopreservation are lower than fresh oocytes and embryos, and improvements are needed. The goal is to develop more effective cryopreservation techniques to enhance reproductive potential, establish oocyte banks, and facilitate international transport of oocytes and embryos. Identifying and addressing obstacles in cryopreservation can lead to better outcomes and encourage further research in assisted reproductive technologies for humans and animals.