Marcos de Lima, MD, University Hospitals Cleveland Medical Center, Cleveland, OH, talks on the main aims and methods of his study on the comparable results seen in oral versus intravenous busulfan in patients undergoing hematopoietic stem cell transplantation (HSCT), with the exception of earlier onset of mucositis, and goes on to share the initial findings of this study. This interview took place at the 5th International Congress on Controversies in Stem Cell Transplantation and Cellular Therapies (COSTEM) 2019, held in Berlin, Germany.