Although computed tomography (CT) of the thorax has been compared to plain chest radiography and bronchography for demonstration of central bronchiectasis (CB) in allergic bronchopulmonary aspergillosis (ABPA), the CT presentation of the disease is yet to be highlighted. With this in view, the CT appearances in 23 patients with ABPA were evaluated. The scans were assessed for bronchial, parenchymal and pleural abnormalities. Central bronchiectasis was identified in all patients, involving 114 (85%) of the 134 lobes and 210 (52%) of the 406 segments studied. Other bronchial abnormalities such as dilated and totally occluded bronchi (11 patients), air-fluid levels within dilated bronchi (five patients), bronchial wall thickening (10 patients) and parallel-line shadows (seven patients) were also observed. Parenchymal abnormalities, which had a predilection for upper lobes, included consolidation in 10 (43%) patients, collapse in four (17%) patients and parenchymal scarring in 19 (83%) patients. A total of six cavities were seen in three (13%) patients, and an emphysematous bullae was detected in one (4%) patient. The pleura was involved in 10 (43%) patients. Ipsilateral pleural effusion with collapse was observed in one patient, while in nine other patients, parenchymal, lesions extended up to the pleura. Concomitant allergic Aspergillus sinusitis (AAS) was also detected in three (13%) of the 23 patients. Computed tomography of the thorax in patients with ABPA provides a sensitive method for the assessment of bronchial, parenchymal and pleural abnormalities, and should constitute a part of the diagnostic work of the disease.