The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) was established in October 2001 to conduct large multi-institutional clinical trials.  The trials will address important issues in hematopoietic stem cell transplantation (HSCT), thereby furthering understanding of the best possible treatment approaches.  Participating BMT CTN investigators collaborate through an organization designed to maintain continuity of operations, to facilitate effective communication and cooperation among participating transplant centers and with collaborators at the National Institutes of Health, and to offer trials participation to patients in all regions of the U.S.