Fertility preservation is now recognized as the most essential quality of life issue in young cancer survivors. This chapter discusses three urgent and critical problems involved with ovarian tissue cryopreservation and transplantation (cryoin-jury, ischemic tissue damage, cancer cell transmission). The risk of cancer cell transmission is a serious safety issue related to ovarian autotransplantation in cancer patient. There are three strategies, at least in theory, to mature follicles in frozen stored ovarian tissue: autotransplantation; xenotransplantation; and in-vitro culture. Recently, significant progress has been made in immature follicle culture techniques. As an alternative to ovarian tissue transplantation, whole ovary transplantation has been explored. In theory, whole intact ovary transplantation with vascular anastomosis can restore the full function of the ovary. The main challenge of whole ovary transplantation for fertility preservation is the development of effective cryotechnology for the whole organ.