Summary: More than 30,000 people are diagnosed annually with leukemia or other blood, metabolic, or immune system disorders, many of whom may die without stem cell transplants, using stem cells from bone marrow or another source. When a patient needs a transplant of donated stem cells and no genetically compatible related donor is available, the National Bone Marrow Donor Registry may help the patient search for compatible stem cells from unrelated donors. The National Bone Marrow Registry Reauthorization Act of 1998 required, among other things, that the Registry carry out a donor recruitment program giving priority to minority and underrepresented donor populations, ensure efficiency of operations, and verify compliance with standards by organizations that participate in the Registry. From 1998, when the National Bone Marrow Registry Reauthorization Act was enacted, through 2001, the number of stem cell donors on the Registry increased for all racial and ethnic groups. Although the exact number of patients in need of transplants is not known, estimates suggest that about one-third of them use the Registry to search for donors. The organizations that are involved in transplantation and participate in the National Marrow Donor Program (NMDP) network generally adhere to NMDP's standards and procedures. In 2001, NMDP required 24 centers to take corrective actions because they did not meet its standards.