Over 80 percent of patients with invasive pulmonary aspergillosis (IPA) undergoing intensive antileukemic chemotherapy in a recent two-year period survived the pulmonary infection as a result of early diagnosis and aggressive therapy with high-dose amphotericin B and 5-fluorocytosine. CT played an important role in establishing the early diagnosis of IPA and affected management. Since our original communication describing the CT findings of IPA, we have added ten new cases, each subsequently substantiated by lung biopsy (two), autopsy (two), and/or positive cultures of sputum or extrapulmonary sites (seven). The CT halo sign, or zone of lower attenuation surrounding a pulmonary mass, was present in eight of nine patients with early CT scans obtained during bone marrow aplasia. Characteristic CT progression from multiple fluffy masses to cavitation or air crescent formation suggested IPA in five of seven patients with serial CT scans. CT directly affected patient management in seven of ten cases. Scan findings were one criterion for increasing to high-dose amphotericin B or for adding 5-fluorocytosine. CT characteristics of healing IPA lesions were similar to resolving pulmonary infarcts and were used to monitor disease activity in patients on long-term amphotericin B and prior to retreatment chemotherapy.