On November 1, 1998, the American Rare Donor Program (ARDP) was formed after merging the ARC Rare Donor Registry and the AABB Rare Donor File. Currently, both AABB and ARC provide funding for the program. The associated computer database is maintained by the American Red Cross (ARC) and is accessible by the ARDP staff at the Philadelphia, PA site. Although the ARDP specifically deals with rare donors and rare patient requests, the rarest blood product is truly that product that is unavailable when needed. It is through the dedicated efforts of donors, technologists, volunteers, office staff, doctors, nurses, international contacts, couriers, and even airport customs staff, that the blood supply is maintained and the ARDP can be effective. Some of the high-level case studies to be presented will illustrate some of these very interesting and complex scenarios that supplement the background information on how the ARDP process is executed.