Invasive pulmonary aspergillosis (IPA) in the presence of hematologic malignancies is an increasingly common condition characterized by high morbidity and mortality. Plain chest films are a valuable tool for diagnosis but the radiologist must be familiar with the morphological features of the disease to interpret radiographic abnormalities and to differentiate IPA from opportunistic pneumonia. The chest films of 16 leukemia and IPA patients performed from January 1987 to September 1993 were reviewed. The natural course of infection from its early stage (nodular lesions) to the subsequent phases when eventual medullary recovery plays a critical role was thus traced. Our major finding was related to the histogenesis of primary pulmonary lesions: the most common features we observed--i.e., the spherical rather than triangular shape of necrosis areas, with no relationship to the pleura or scissural delimitation suggest that supposed ischemia from vascular infiltration cannot be the only pathogenetic factor of pulmonary injury, in spite of the well-known angioinvasivity of the fungus Aspergillus.