ABSTRACT: The prognosis of invasive aspergillosis in immunocompromised hosts is extremely gruesome. We described a 56-year-old man who suffered from invasive pulmonary aspergillosis. He had immunological impairment caused by neutropenia due to hemophagocytic syndrome and high dose glucocorticoid therapy. On the day after his chest radiograph revealed abnormal shadow in the left lung, we detectedAspergillushyphae in his Gram's-stained sputum under a microscope. Thanks to this prompt diagnosis, we could save him without any sequelae. Microscopic examination of sputum without delay is highly recommended when invasive pulmonary aspergillosis is suspected in patients at risk for this macabre disease.