Between 80 and 100 allogeneic stem cell transplants (allo-HSCT) are performed every year at the NIH to treat a variety of malignant and nonmalignant conditions. The current transplant protocols at the NIH focus on research regarding the response of the underlying disease, the development of graft versus host disease (GVHD) as well as the feasibility and safety of a variety of transplant strategies. Many clinically significant complications are considered to be part of the transplant process and are not studied systematically. Even when they are studied, the diverse institute-based protocols differ on the range of complications captured and the amount of information collected on them. This leads to knowledge gaps regarding the incidence and risk factors for complications in the various protocols.