Countries where there are many institutions working in the field of stem cell donation and transplantation usually have a central registry (hub) which coordinates and facilitates the complex processes of searching for donors and transplantation. In Germany, this task was transferred to the ZKRD (German National Bone Marrow Donor Registry) in 1992. The search-relevant data from all voluntary donors registered with the regional and national donor centers in Germany is collected anonymously at the ZKRD. During a donor search, this data is compared against that of the patient in question and the search center is informed of the potentially suitable donors. Based on their roles, a distinction is made between registry and donor center even if some donor centers include the word “registry” in their official titles.