A 51-year-old female with acute myeloid leukemia was admitted to our hospital in December 2001. Though she had undergone two courses of induction chemotherapy (idarubicin hydrochloride + cytarabine), she failed to achieve a complete remission. In April 2002, while in non-complete remission, she subsequently underwent total body irradiation (TBI) and treatment with cyclophosphamide (CY) and etoposide (VP-16) before receiving an allogeneic peripheral blood stem cell transplant from her HLA-identical brother. For graft-versus-host disease (GVHD) prophylaxis, she was given tacrolimus and methotrexate. The infused CD34 positive cells provided 8.1 x 10(6) cells per kg. Engraftment was obtained on post-transplant day 14, and there was no evidence of clinical acute GVHD. The use of tacrolimus was discontinued on post-transplant day 60. As there was no occurrence of clinical acute GVHD, the patient received a donor lymphocyte infusion (CD3 cells 0.57 X 10(7) cells per kg) on post-transplant day 105. On day 132, however, she complained of coughing and fever, and on day 135, she was admitted to our hospital again for dyspnea. A CT scan demonstrated ground-glass opacity in the right pulmonary lobe. After considering her clinical course, symptoms, blood gas, CT scans, etc., we suspected interstitial pneumonia. The dyspnea progressively worsened, however, and despite the use of mechanical ventilation from day 143, the patient died on day 149. From the day she was admitted till the day she was intubated, she was unable to produce sputum. Autopsy findings revealed yellow-white tracheal pseudomembranes, as well as Aspergillus hyphae in the trachea, bronchus, and bilateral lungs. These findings are characteristic of Aspergillus tracheobronchitis. The clinical course of Aspergillus tracheobronchitis in allogeneic stem cell transplant recipients is, however, different from that of the usual invasive Aspergillus infection, and although Aspergillus tracheobronchitis is a very rare disease, attention should be paid to the possibility of its occurrence.