The Aspergillus species produces metabolic products that play a significant role in the destructive processes in the lung. We experie nced a case of chronic necrotizing pulmonary aspergillosis caused by an Aspergillus niger infection, which contained numerous calcium oxalate crystals in the necrotic lung tissue. A 46-year-old man, who had a history of pulmonary tuberculosis, presented with high fever, intermittent hemoptysis and pulmonary infiltrations with a cavity indicated by the chest radiograph. Despite being treated with several antibiotics and anti-tuberculosis regimens, the high fever continued. The sputum cultures yielded A. niger repeatedly, and intravenous amphotericin B was then introduced. The pathological specimen obtained by a transbron chial lung biopsy revealed numerous calcium oxalate crystals in a background of acute inflam matory exudates with no identification of the organism. Intravenous amphotericin B was con tinued at a total dose of 1600 mg, and at that time he was afebrile, although the intermittent hemoptysis continued. On the 63^rd hospital day, a massive hemoptysis (about 800 mL) developed, which could not be controlled despite embolizing the left bronchial artery. He died of respiratory failure the next day. It is believed that the oxalic acid produced by A. niger was the main cause of the patient's pulmonary injury and the ensuing massive hemoptysis.