The ubiquitous Aspergillus fungus has numerous manifestations when associated with lung disease (primary Aspergillus pneumonia, aspergilloma, allergic bronchopulmonary aspergillosis, and invasive Aspergillus). This fungus also can colonize preexisting lung disease in an indolent manner and then acutely assume a more invasive nature. Although the species Aspergillus niger is infrequently encountered, the endobronchial visualization of black necrotic debris or a fungus ball or the finding of black acidic sputum or pleural fluid suggests the presence of A niger and the destructive by-product of its fermentation, oxalic acid.