The international exchange of cord blood units (CBUs) for transplantation has brought new challenges to the stem cell donor registries involved in the exchange of BM and PBSCs. The unique properties of cord blood cells and differences in the search processes between CBUs and adult unrelated donors has required registries responsible for cord blood bank (CBB) networks to review their current practices and to develop new processes to accommodate for the provision of CBUs. This paper describes the aims and activities of the World Marrow Donor Association (WMDA) Cord Blood Working Group (CBWG) which was established in 2007 to gather and exchange information about cord blood registry needs and activities, and to develop guidelines to support and promote safe effective international exchange of unrelated CBUs for transplantation.