To investigate the clinical manifestations of Aspergillus infections in lung transplant recipients, we reviewed the mycology and autopsy reports of all double (DLT=93) and single (SLT=48) lung transplant recipients from November 1983 to May 1993. Positive Aspergillus cultures were identified in 22% of the recipients (DLT=21, SLT=10). Colonization alone was present in 19 recipients (DLT=16, SLT=3). Complicated Aspergillus infection included Aspergillus bronchitis (DLT=1, SLT=1), aspergilloma (SLT=2), pulmonary invasive aspergillosis (DLT=1, SLT=2), disseminated aspergillosis (DLT=1, SLT=2), empyema (DLT=1), and a retroperitoneal abscess (DLT=1). Symptoms were seen only in patients with complicated lung infections and CXR abnormalities began in the native lung of four SLT recipients. Twenty patients survived (DLT=17, SLT=3) and 11 died (DLT=4, SLT=7) of disseminated aspergillosis (SLT=2), pulmonary invasive disease (DLT=1), bronchiolitis obliterans (DLT=2, SLT=2, CMV pneumonitis (SLT=1), diffuse alveolar damage (SLT=2), and hyperacute rejection (DLT=1). Complicated infection and mortality were more common in SLTs than DLTs (P<0.05). We conclude that infection with Aspergillus is not infrequent in the lung transplantation population. Single lung recipients develop more complicated infection than double lung recipients after Aspergillus infection with native lung being a potential source of infection.