This chapter talks about fertility cryopreservation for pre- and postpubertal male and female adolescents and is written in the context of fertility preservation for cancer patients. For postpubertal males, the commonest option is freezing of ejaculated sperm before cancer treatment, followed by artificial insemination, in vitro fertilization (IVF), or intracytoplasmic sperm injection (ICSI) using thawed sperm. Fertility preservation for prepubertal male cancer patients is technically and ethically more complex than for postpubertal males. Like their male counterparts, postpubertal female patients have the advantage of producing mature gametes in their effort to preserve fertility before anti-cancer therapy. A dilemma in fertility cryopreservation arises from the concern that cancer patients may pass on causative or predisposing factors in their gamete and produce cancerous off spring or off spring with higher risks of cancer. This is particularly true for high-penetrance cancer-predisposition syndromes such as hereditary retinoblastoma and breast cancer.