A 26-year-old man who smoked and had a long history of poorly controlled asthma and severe environmental allergies was admitted for an exacerbation of asthma. He reported no recent hospitalizations or exposure to tuberculosis and for more than a year had not been taking any medications. A computed tomographic scan was obtained to elucidate multilobar infiltrates that were seen on chest radiographs. Areas of tubular (Panel A, arrows) and cystic (Panel A, arrowhead) bronchiectasis, predominantly in the upper lobes, and bilateral mucous plugging (Panel B, arrows) were seen, along with mediastinal and hilar lymphadenopathy. His white-cell count was 8000 per cubic millimeter with 8% eosinophils, and his IgE level was 21,494 IU per milliliter (normal range, 0 to 150). A test for human immunodeficiency virus was negative. Genetic testing for cystic fibrosis was negative for the 103 most common mutations. A sputum culture grew Aspergillus fumigatus. Serum aspergillus precipitins were positive, with an index of IgE to A. fumigatus of 9.6 (normal, <2) and an index of IgG to A. fumigatus of 2.4 (normal, <2). Taken together, these findings were consistent with a diagnosis of allergic bronchopulmonary aspergillosis. Clinical improvement was seen after a taper of glucocorticoids over a period of 2 months. Subsequently, the patient was lost to follow-up.