Patients with chronic granulomatous disease (CGD) complicated by antimycotics-refractory invasive aspergillosis have an extremely poor prognosis if they cannot undergo allogeneic hematopoietic stem cell transplantation from a suitable related donor while in good clinical condition. We successfully treated a 20-year-old man with very rare McLeod phenotype CGD with reduced-intensity conditioning and unrelated-donor umbilical cord blood transplantation. We postulate that reduced-intensity conditioning-allogeneic hematopoietic stem cell transplantation is a promising therapeutic strategy for patients with CGD even if only unrelated-donor umbilical cord blood is available.