Patients with cancer are at risk of loss of gonadal function due to the cancer treatment. Chemo- and radiation therapy are known to induce gonadal failure in both men and women and especially treatment with alkylating agents and/or abdominal or testicular radiation therapy poses a high risk. Methods exist to preserve fertility and these should be discussed with and offered to the patient if necessary and possible. For men, cryopreservation of semen is simple, non-invasive and low-cost. For women, cryopreservation of oocytes, embryos or ovarian tissue is an option in order to preserve fertility.