In contrast to unrelated donors who are counselled and examined according to international guidelines, related donors of allogeneic bone marrow (BM) or mobilized peripheral blood stem cells (PBSC) often are recruited, examined and followed otherwise. Currently, mostly PBSC instead of BM donation is used. The higher CD34+ yield is preferred for non-myeloablated recipients, allowing transplantation of older patients. Consequently related sibling donors are aging and prone to suffer more co-morbidity as compared to unrelated donors. With respect to counselling it is obvious that donor recruitment and motivation between related and unrelated donors differ. The related donor however needs protection by an independent physician safeguarding the health of the donor. Although financial and logistic reasons may play a role, several differences between related and unrelated donor management are eligible for harmonization. In addition it is important to reach agreement among donor centres on uniform decisions for deferral and long-term follow-up. This requires exchange of information, not only of serious adverse reactions but also of potential hazardous situations, in order to develop more evidence-based recommendations.