The development of modern medicine made it more likely for oncological patients to survive. Also, there are a lot of young female patients with a persistent wish for kids. After an aggressive chemotherapy, premature ovarian failure (POF) is a possible consequence of the therapy. Therefore, efficient fertility protective interventions are requested. The transplantation of ovarian tissue after cryopreservation is a valuable method, which could remain fertility after POF induced by cytotoxic therapies. Especially for girls suffering from cancer, who didn't reach puberty yet, cryopreservation of ovarian tissue is the only opportunity to preserve a chance of restoring fertility after POF.