Advances in the diagnosis and treatment of childhood, adolescent and adult cancer have greatly increased the life expectancy of premenopausal women with cancer. The ovaries are very sensitive to cytotoxic treatment, especially to alkylating agents. The only established method of fertility preservation is embryo cryopreservation according to the Ethics Committee of the American Society for Reproductive Medicine (2005), but this option requires the patient to be of pubertal age, have a partner or use donor sperm and be able to undergo a cycle of ovarian stimulation, which is not possible when the chemotherapy has to be initiated immediately or when stimulation is contraindicated, according to the type of cancer. For patients who need immediate chemotherapy, cryopreservation of ovarian tissue is the only possible alternative. This article reports the techniques and results of orthotopic transplantation of cryopreserved ovarian tissue. Among almost 30 cases reported in the literature, six live births have been achieved to date.