Infections and rejection have long been the leading causes of morbidity and mortality in transplant recipients. Although recent advances in immunosuppression, prophylaxis, and treatment of infections such as cytomegalovirus have resulted in improved outcome in transplant recipients, invasive aspergillosis remains a scourge of transplantation medicine. Invasive aspergillosis has a mortality in this patient population of up to 90% and accounts for 10%-15% of all deaths of transplant recipients in the first year after transplant. Of more than 20,000 transplant recipients who have been reported, incidence of invasive aspergillosis has ranged from 0.7% in kidney transplant recipients to 8.4% in lung transplant recipients. Definite risk factors for development of invasive aspergillosis exist, including delayed engraftment and severe graft-versus-host disease in bone marrow transplant recipients and poor graft function, cytomegalovirus infection, and renal failure in solid-organ transplant recipients. Although a number of prophylactic regimens are in widespread use, none has been shown conclusively to reduce the incidence of invasive aspergillosis. Reducing environmental exposure to Aspergillus, early diagnosis of the infection by means of antigen detection in serum, and use of high-resolution computed tomography are alternatives to use of prophylaxis but have not been systematically evaluated. New treatment options include early surgical intervention in cases of localized disease; lipid preparations of amphotericin, itraconazole, or voriconazole; and immunotherapy with G-CSF or GM-CSF and interferon-gamma.