These guidelines concern situations where a donor is asked to provide a subsequent donation for the same recipient the donor previously donated bone marrow or peripheral blood stem cells (PBSC) to, or when asked to donate to another patient. The guidelines address only requests for subsequent donation of bone marrow, PBSC, nonmobilised mononuclear cell leukapheresis or whole blood units. When there is a need for a second donation, the Norwegian Bone Marrow Donor Registry will communicate the procedure for this inquiry with the requesting center.