Wilford Hall Medical Center at Lackland Air Force Base is the only military medical center in the United States at which allogeneic hematopoietic stem cell transplants (HSCT) are performed. Through May 2001, 367 patients, including 163 active duty service members, have received allogeneic HSCT from related donors. We performed a retrospective review of the outcomes of allogeneic HSCT in active duty members to determine what proportion was returned to full-time military service after HSCT and to delineate the factors associated with successful return to military service. Twenty-one percent of service members who received allogeneic HSCT were returned to active duty at some point after treatment. Age, sex, branch of service, and rank had no significant influence on return to duty status. When adjusted for age and rank, the only significant predictor of successful return to active duty was a diagnosis of chronic myelogenous leukemia. Although individuals with good risk diseases such as aplastic anemia, myelodysplastic syndrome, paroxymal nocturnal hemoglobinuria, and acute myelogenous leukemia in first complete remission have also been returned active duty after HSCT, these diagnoses were not statistically predictive of a return to active duty. We conclude that it may be possible to predict which service members will return to active duty after allogeneic HSCT based on the disease for which HSCT is being performed. Most importantly, active duty service members need not be a priori medically retired after HSCT, and each return to duty decision must be individualized.