Every year, many people diagnosed with diseases such as leukemia and lymphoma require transplants of stem cells from umbilical cord blood or other sources. The Stem Cell Therapeutic and Research Act of 2005 authorized funding for banking 150,000 new units of high quality and genetically diverse cord blood and directed the Department of Health and Human Services (HHS) to contract with cord blood banks to assist in cord blood collection. HHS, through the Health Resources and Services Administration (HRSA), established the National Cord Blood Inventory (NCBI) program to support banking of cord blood units and contracted with 13 cord blood banks to bank these units. The 2010 reauthorization required GAO to report on efforts to increase cord blood unit collection for the NCBI. As of May 2011, HRSA had reimbursed banks for over 41,000 units banked for the NCBI. In this report, GAO describes (1) practices identified to increase banking of cord blood units for the NCBI and related challenges and (2) practices cord blood banks are using to lower costs and improve the efficiency of cord blood banking and associated challenges. To do so, GAO reviewed relevant regulations and documents, and interviewed officials from pertinent organizations. These included officials from HRSA, the Food and Drug Administration (FDA), which is responsible for regulating cord blood used in transplants for patients who are not related to the donor, the National Marrow Donor Program (NMDP), which operates a national registry of cord blood units and other sources of stem cells, and the 13 banks with contracts to bank cord blood units for the NCBI..