It is possible that you would match more than one patient needing a transplant but it would be rare that you are asked to donate again to a different patient. However, you may be asked to donate bone marrow twice to one patient if the first transplant did not “take”. After donating you will be retired from the registry for two years. At the end of this period you will automatically be re-activated in the registry system unless you notify your Donor Support Coordinator that you no longer wish to remain on the registry.