For patients, transplantation of ovarian tissue has become an attractive option to overcome the risk of pending premature menopause caused by various clinical conditions. This chapter describes different aspects of ovarian tissue transplantation including history, basic experiments, and the results of clinical studies. To date, ovarian tissue has been successfully cryopreserved and transplanted into rodents, sheep, rabbits, and marmoset monkeys. Successful fertilization and pregnancy after oocyte collection from fresh transplanted ovarian tissue has been described in a monkey. Transplantation of ovarian tissue has been tested in orthotopic and heterotopic sites. Ovarian cryobanking allows for the storage of abundant primordial follicles containing small, less-differentiated acolytes. Cancer treatment, including high-dose chemotherapy and abdominal irradiation, is associated with ovarian toxicity as a common long-term side effect. Post-chemotherapy, patients are routinely followed by the oncological/hematological clinics. Research on both the indications for ovarian tissue transplantation and on technique improvement should continue.