Invasive aspergillosis is a major cause of morbidity and mortality in immunocompromised patients receiving intensive care. The double-sandwich ELISA for galactomannan is reported to have a high sensitivity (96.5%) for the detection of invasive aspergillosis when a cut-off value of 0.8 ng/ml is used. However, we have experienced a case of lethal disseminated aspergillosis in a patient that presented with a negative galactomannan (GM) test and persistent elevation of beta-D glucan (BG) levels. A 63-year-old female was admitted to our Intensive Care Unit (ICU) in acute respiratory failure and elevated BG. She had been receiving medication for Good-pasture syndrome based on anti-glomerular basement membrane antibodies and myeloperoxidase-antineutrophil cytoplasmic antibodies for 9 months and was receiving long-term prednisolone therapy (20 mg/day). On admission, her trachea was immediately intubated, and a PCR analysis of the bronchoalveolar lavage sample revealed Pneumocystis jiroveci. Trimethoprimsulfamethoxazole therapy was started for Pneumocystis pneumonia. The levels of BG remained elevated (> 100 pg/ml) during the treatment period despite the clinical resolution of Pneumocystis pneumonia, raising concerns of another complicated invasive fungal disease; consequently, fosfluconazole was administered empirically. The serum BG levels, however, did not decrease. Blood cultures did not detect a fungal infection. Serum GM levels measured by a double-sandwich ELISA on the 6th, 11th, and 24th days in the ICU were negative (< 0.2 ng/ml). The patient ultimately died of multiple organ failure on the 45th ICU day. Postmortem examination revealed a disseminated fungal infection with aggressive vascular invasion of the lungs, heart, and brain. In situ hybridization with a 568-bp probe of the alkaline proteinase sequence of Aspergillus fumigatus showed specific positive staining within the fungus present in the infected lung tissue, revealing that this patient may have had a systemic infection by A. fumigatus or A. flavus. This is a case of serum GM-negative disseminated aspergillosis pathologically proven by autopsy. Persistent elevated BG levels (> 100 pg/ml) refractory to trimethoprim-sulfamethoxazole and fosfluconazole may suggest possible Aspergillus infection and should prompt the initiation of empiric anti-aspergillosis therapies in patients at risk for fungal infection.