The medical treatment of various cancers may, as long-term sequelae, cause infertility in girls and young women. In order to preserve the fertility of such women, techniques to cryopreserve ovarian tissue have gained considerable interest during recent years. The ovarian tissue is cryopreserved before cancer treatment is commenced, and first replaced when the woman has been cured. Based on the successful results from the use of this technique in test animals, where normal live young have been born, cryopreservation of human ovarian tissue has been initiated in a number of fertility clinics worldwide over the last few years. So far, only two women have experienced transplantation of cryopreserved ovarian tissue. Menstrual cycles and oestradiol production were restored in both women, but restoration of fertility have not yet been demonstrated. This review describes the technique and its present possibilities and limitations. The legal aspects in Denmark are presented and some ethical aspects described.