The authors reviewed 55 pairs of chest radiographs and computed tomographic (CT) studies obtained in 33 febrile bone marrow transplant (BMT) recipients. The images were read separately, without knowledge of the clinical diagnosis. Twenty-one episodes of fungal infection were documented. One chest radiograph showed a pneumonia-like opacity, and 17 showed nodular opacities, five with cavitation. In 20 of 21 episodes, CT showed nodules with cavitation (n = 7), halo (n = 4), hazy margin (n = 5), air bronchogram (n = 2), cluster of fluffy nodules (n = 1), or sharp margin (n = 1). In none of the nine bacteremic episodes, however, were there opacities on chest radiographs or CT studies. CT studies demonstrating complicated nodules in febrile BMT patients strongly suggest a fungal infection, whereas negative CT studies suggest bacteremia or non-filamentous fungal infection of nonpulmonary origin. CT appears to add useful information to radiographic analysis during the assessment of febrile episodes in BMT patients, especially when invasive diagnostic procedures pose a high risk.