Metabolic products of Aspergillus species may play a significant role in the pulmonary destructive process. We describe a patient who died of respiratory failure, in whom postmortem examination revealed aspergilloma and numerous calcium oxalate crystals around the aspergilloma, as well as extensive consolidation areas. An-87-year-old man with a history of pulmonary tuberculosis and asbestos exposure was admitted to our hospital with fever and hemosputum. Chest radiograph on admission showed several small cavities in the right upper lung fields, but did not indicate the presence of a fungus ball. The patient was treated with several antibiotics, but his symptoms, and findings for inflammatory indicators and findings on chest radiographs deteriorated, and he died of respiratory failure 45 days after admission. Postmortem examination of the thoracic cavities showed marked involvement with extensive adhesions, fibrosis, caseation, and necrotic tissue. Aspergillus niger formed a mass in the right upper cavity and a localized invasion surrounding the cavity wall, but no organisms were detected in the left consolidation area. Numerous calcium oxalate crystals were found in the cavity wall, as well as an extensive consolidation area. We consider that oxalic acid produced by Aspergillus was the main cause of the patient's respiratory failure.