With the improvement of the outcome, the number of long-term survivors of hematopoietic stem cell transplantation (HSCT) is continuously increasing. However, there is still a high burden of late morbidity and mortality. Two-thirds of the transplant survivors develop at least one late effect interfering with their physical or psychological health. Infertility is common after myeloablative HSCT conditioned with total body irradiation and high doses of gonadotoxic drugs. Other factors, such as the age of the patient at transplantation, the treatment modality received before HSCT or the onset of chronic graft versus host disease, may play an additional role. Accordingly, the number of pregnancies observed after HSCT is very low when compared to a general population in childbearing age. Furthermore, complications during pregnancy and at delivery occur significantly more frequently, probably because of the uterine damages caused by irradiation therapy. However, there is no excess of congenital abnormalities observed among newborn children. Today there are good possibilities for fertility preservation. In male patients cryopreservation of sperm, and in female patients cryopreservation of fertilized embryos or of mature oocytes, are well-established treatment options. Patients' and physicians' attitude toward discussion on fertility issues play a key role in the success of fertility preservation after HSCT.