A 72-year-old man with idiopathic pulmonary upper lobe fibrosis who had been followed for a year developed a high fever and yellow sputum in July 2001. Chest radiography and chest computed tomography (CT) showed a rapidly enlarging cavity with an internal mass and infiltration in the left upper lung field. Pulmonary aspergillosis was diagnosed by examination of bronchoalveolar lavage fluid (BALF). Administration of itraconazole improved his condition. The concentrations of surfactant proteins A (SP-A) and D (SP-D) in serum and in BALF were decreased during the clinical course. It is known that SP-A and SP-D are critical factors for host defense against aspergillus. The lowering of SP-A and SP-D in the serum and BALF seemed to reflect destructive changes of lung structure and impaired innate lung immunity that could to lead invasive pulmonary aspergillosis.