Since its founding in 1986, the NMDP has facilitated more than 16,000 transplants for patients with blood disorders such as leukemia and aplastic anemia, as well as immune system disorders and genetic disorders. The donors who provided the blood stem cells for these transplants came from the NMDP Registry, the world's largest and most diverse registry of potential blood stem cell donors. Initiating a search of the NMDP Registry for an HLA-matched unrelated donor is as simple as submitting to the NMDP a patient's HLA typing results along with basic demographic and disease information. If a suitable donor is identified, the NMDP coordinates the steps needed to bring the donated stem cells--whether they be marrow, PBSC, or cord blood--to a patient. After reading this article, physicians should have a greater understanding of the complicated process needed to bring about an unrelated donor stem cell transplant. A better understanding of the role the NMDP plays in unrelated donor stem cell transplantation reduces the chances that physicians and patients will have unrealistic expectations about the process. To initiate a preliminary search of the NMDP Registry, contact the NMDP Office of Patient Advocacy toll-free at 1-888-999-6743. A preliminary search reqest form can also be submitted via the NMDP website:www.marrow.org